diff --git a/.pending/breaking/sdk/4521-Flatten-x-bank- b/.pending/breaking/sdk/4521-Flatten-x-bank-
new file mode 100644
index 000000000000..09dfd25e05ed
--- /dev/null
+++ b/.pending/breaking/sdk/4521-Flatten-x-bank-
@@ -0,0 +1 @@
+#4521 Flatten x/bank structure by hiding module internals.
diff --git a/simapp/sim_test.go b/simapp/sim_test.go
index 8ee536e554df..33e00cb576be 100644
--- a/simapp/sim_test.go
+++ b/simapp/sim_test.go
@@ -26,7 +26,6 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/auth/genaccounts"
 	authsim "github.com/cosmos/cosmos-sdk/x/auth/simulation"
 	"github.com/cosmos/cosmos-sdk/x/bank"
-	banksim "github.com/cosmos/cosmos-sdk/x/bank/simulation"
 	distr "github.com/cosmos/cosmos-sdk/x/distribution"
 	distrsim "github.com/cosmos/cosmos-sdk/x/distribution/simulation"
 	"github.com/cosmos/cosmos-sdk/x/gov"
@@ -605,7 +604,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			banksim.SimulateMsgSend(app.accountKeeper, app.bankKeeper),
+			bank.SimulateMsgSend(app.accountKeeper, app.bankKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
@@ -616,7 +615,7 @@ func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
 					})
 				return v
 			}(nil),
-			banksim.SimulateSingleInputMsgMultiSend(app.accountKeeper, app.bankKeeper),
+			bank.SimulateSingleInputMsgMultiSend(app.accountKeeper, app.bankKeeper),
 		},
 		{
 			func(_ *rand.Rand) int {
diff --git a/x/bank/alias.go b/x/bank/alias.go
index 595c3ab61425..75f71aaa018f 100644
--- a/x/bank/alias.go
+++ b/x/bank/alias.go
@@ -5,7 +5,8 @@
 package bank
 
 import (
-	"github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/keeper"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/types"
 )
 
 const (
@@ -15,22 +16,19 @@ const (
 	ModuleName               = types.ModuleName
 	RouterKey                = types.RouterKey
 	DefaultParamspace        = types.DefaultParamspace
-	DefaultSendEnabled       = types.DefaultSendEnabled
 )
 
 var (
 	// functions aliases
-	RegisterCodec          = types.RegisterCodec
-	ErrNoInputs            = types.ErrNoInputs
-	ErrNoOutputs           = types.ErrNoOutputs
-	ErrInputOutputMismatch = types.ErrInputOutputMismatch
-	ErrSendDisabled        = types.ErrSendDisabled
-	NewMsgSend             = types.NewMsgSend
-	NewMsgMultiSend        = types.NewMsgMultiSend
-	NewInput               = types.NewInput
-	NewOutput              = types.NewOutput
-	ValidateInputsOutputs  = types.ValidateInputsOutputs
-	ParamKeyTable          = types.ParamKeyTable
+	RegisterCodec                   = types.RegisterCodec
+	ErrNoInputs                     = types.ErrNoInputs
+	ErrNoOutputs                    = types.ErrNoOutputs
+	ErrInputOutputMismatch          = types.ErrInputOutputMismatch
+	ErrSendDisabled                 = types.ErrSendDisabled
+	NewBaseKeeper                   = keeper.NewBaseKeeper
+	NewInput                        = types.NewInput
+	NewOutput                       = types.NewOutput
+	ParamKeyTable                   = types.ParamKeyTable
 
 	// variable aliases
 	ModuleCdc                = types.ModuleCdc
@@ -38,6 +36,8 @@ var (
 )
 
 type (
+	BaseKeeper   = keeper.BaseKeeper // ibc module depends on this
+	Keeper       = keeper.Keeper
 	MsgSend      = types.MsgSend
 	MsgMultiSend = types.MsgMultiSend
 	Input        = types.Input
diff --git a/x/bank/app_test.go b/x/bank/app_test.go
index 651021eadb9d..066d406413bf 100644
--- a/x/bank/app_test.go
+++ b/x/bank/app_test.go
@@ -1,11 +1,13 @@
-package bank
+package bank_test
 
 import (
 	"testing"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
-	"github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/cosmos/cosmos-sdk/x/bank"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/keeper"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/types"
 	"github.com/cosmos/cosmos-sdk/x/mock"
 
 	"github.com/stretchr/testify/require"
@@ -95,11 +97,11 @@ func getMockApp(t *testing.T) *mock.App {
 }
 
 // overwrite the mock init chainer
-func getInitChainer(mapp *mock.App, keeper BaseKeeper) sdk.InitChainer {
+func getInitChainer(mapp *mock.App, keeper keeper.BaseKeeper) sdk.InitChainer {
 	return func(ctx sdk.Context, req abci.RequestInitChain) abci.ResponseInitChain {
 		mapp.InitChainer(ctx, req)
-		bankGenesis := DefaultGenesisState()
-		InitGenesis(ctx, keeper, bankGenesis)
+		bankGenesis := bank.DefaultGenesisState()
+		bank.InitGenesis(ctx, keeper, bankGenesis)
 
 		return abci.ResponseInitChain{}
 	}
diff --git a/x/bank/bench_test.go b/x/bank/bench_test.go
index f4e5042805a2..eb126492e973 100644
--- a/x/bank/bench_test.go
+++ b/x/bank/bench_test.go
@@ -1,4 +1,4 @@
-package bank
+package bank_test
 
 import (
 	"testing"
@@ -7,7 +7,9 @@ import (
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
-	"github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/cosmos/cosmos-sdk/x/bank"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/keeper"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/types"
 	"github.com/cosmos/cosmos-sdk/x/mock"
 )
 
@@ -17,12 +19,12 @@ func getBenchmarkMockApp() (*mock.App, error) {
 	mapp := mock.NewApp()
 
 	types.RegisterCodec(mapp.Cdc)
-	bankKeeper := NewBaseKeeper(
+	bankKeeper := keeper.NewBaseKeeper(
 		mapp.AccountKeeper,
 		mapp.ParamsKeeper.Subspace(types.DefaultParamspace),
 		types.DefaultCodespace,
 	)
-	mapp.Router().AddRoute(types.RouterKey, NewHandler(bankKeeper))
+	mapp.Router().AddRoute(types.RouterKey, bank.NewHandler(bankKeeper))
 	mapp.SetInitChainer(getInitChainer(mapp, bankKeeper))
 
 	err := mapp.CompleteSetup()
diff --git a/x/bank/client/cli/tx.go b/x/bank/client/cli/tx.go
index 86209a51fe64..6d2335256f43 100644
--- a/x/bank/client/cli/tx.go
+++ b/x/bank/client/cli/tx.go
@@ -9,7 +9,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	auth "github.com/cosmos/cosmos-sdk/x/auth"
-	"github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/types"
 )
 
 const (
diff --git a/x/bank/client/rest/tx.go b/x/bank/client/rest/tx.go
index cb8585db0755..682cfcf00d35 100644
--- a/x/bank/client/rest/tx.go
+++ b/x/bank/client/rest/tx.go
@@ -11,7 +11,7 @@ import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/types/rest"
 
-	"github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/types"
 )
 
 // RegisterRoutes - Central function to define routes that get registered by the main application
diff --git a/x/bank/handler.go b/x/bank/handler.go
index 040e440e3da7..a1c4f2adf4a4 100644
--- a/x/bank/handler.go
+++ b/x/bank/handler.go
@@ -4,12 +4,12 @@ import (
 	"fmt"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
-	"github.com/cosmos/cosmos-sdk/x/bank/tags"
-	"github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/keeper"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/types"
 )
 
 // NewHandler returns a handler for "bank" type messages.
-func NewHandler(k Keeper) sdk.Handler {
+func NewHandler(k keeper.Keeper) sdk.Handler {
 	return func(ctx sdk.Context, msg sdk.Msg) sdk.Result {
 		switch msg := msg.(type) {
 		case types.MsgSend:
@@ -26,7 +26,7 @@ func NewHandler(k Keeper) sdk.Handler {
 }
 
 // Handle MsgSend.
-func handleMsgSend(ctx sdk.Context, k Keeper, msg types.MsgSend) sdk.Result {
+func handleMsgSend(ctx sdk.Context, k keeper.Keeper, msg types.MsgSend) sdk.Result {
 	if !k.GetSendEnabled(ctx) {
 		return types.ErrSendDisabled(k.Codespace()).Result()
 	}
@@ -36,9 +36,9 @@ func handleMsgSend(ctx sdk.Context, k Keeper, msg types.MsgSend) sdk.Result {
 	}
 
 	resTags := sdk.NewTags(
-		tags.Category, tags.TxCategory,
-		tags.Sender, msg.FromAddress.String(),
-		tags.Recipient, msg.ToAddress.String(),
+		types.Category, types.TxCategory,
+		types.Sender, msg.FromAddress.String(),
+		types.Recipient, msg.ToAddress.String(),
 	)
 
 	return sdk.Result{
@@ -47,7 +47,7 @@ func handleMsgSend(ctx sdk.Context, k Keeper, msg types.MsgSend) sdk.Result {
 }
 
 // Handle MsgMultiSend.
-func handleMsgMultiSend(ctx sdk.Context, k Keeper, msg types.MsgMultiSend) sdk.Result {
+func handleMsgMultiSend(ctx sdk.Context, k keeper.Keeper, msg types.MsgMultiSend) sdk.Result {
 	// NOTE: totalIn == totalOut should already have been checked
 	if !k.GetSendEnabled(ctx) {
 		return types.ErrSendDisabled(k.Codespace()).Result()
@@ -57,7 +57,7 @@ func handleMsgMultiSend(ctx sdk.Context, k Keeper, msg types.MsgMultiSend) sdk.R
 		return err.Result()
 	}
 
-	resTags = resTags.AppendTag(tags.Category, tags.TxCategory)
+	resTags = resTags.AppendTag(types.Category, types.TxCategory)
 	return sdk.Result{
 		Tags: resTags,
 	}
diff --git a/x/bank/invariants.go b/x/bank/internal/keeper/invariants.go
similarity index 95%
rename from x/bank/invariants.go
rename to x/bank/internal/keeper/invariants.go
index c183c9ebb424..d401c27f5073 100644
--- a/x/bank/invariants.go
+++ b/x/bank/internal/keeper/invariants.go
@@ -1,4 +1,4 @@
-package bank
+package keeper
 
 import (
 	"errors"
@@ -6,7 +6,7 @@ import (
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
-	"github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/types"
 )
 
 // register bank invariants
diff --git a/x/bank/keeper.go b/x/bank/internal/keeper/keeper.go
similarity index 97%
rename from x/bank/keeper.go
rename to x/bank/internal/keeper/keeper.go
index 730c96e070e7..718569fadaef 100644
--- a/x/bank/keeper.go
+++ b/x/bank/internal/keeper/keeper.go
@@ -1,4 +1,4 @@
-package bank
+package keeper
 
 import (
 	"fmt"
@@ -6,8 +6,7 @@ import (
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
-	"github.com/cosmos/cosmos-sdk/x/bank/tags"
-	"github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/types"
 	"github.com/cosmos/cosmos-sdk/x/params"
 )
 
@@ -340,7 +339,7 @@ func inputOutputCoins(ctx sdk.Context, am auth.AccountKeeper, inputs []types.Inp
 		}
 
 		allTags = allTags.AppendTag(
-			tags.Sender, in.Address.String(),
+			types.Sender, in.Address.String(),
 		)
 	}
 
@@ -350,7 +349,7 @@ func inputOutputCoins(ctx sdk.Context, am auth.AccountKeeper, inputs []types.Inp
 			return nil, err
 		}
 		allTags = allTags.AppendTag(
-			tags.Recipient, out.Address.String(),
+			types.Recipient, out.Address.String(),
 		)
 	}
 
@@ -386,7 +385,7 @@ func delegateCoins(
 	setAccount(ctx, ak, acc)
 
 	return sdk.NewTags(
-		sdk.TagAction, tags.ActionDelegateCoins,
+		sdk.TagAction, types.ActionDelegateCoins,
 		sdk.TagDelegator, addr.String(),
 	), nil
 }
@@ -411,7 +410,7 @@ func undelegateCoins(
 	setAccount(ctx, ak, acc)
 
 	return sdk.NewTags(
-		sdk.TagAction, tags.ActionUndelegateCoins,
+		sdk.TagAction, types.ActionUndelegateCoins,
 		sdk.TagDelegator, addr.String(),
 	), nil
 }
diff --git a/x/bank/keeper_test.go b/x/bank/internal/keeper/keeper_test.go
similarity index 93%
rename from x/bank/keeper_test.go
rename to x/bank/internal/keeper/keeper_test.go
index c658d5e46e9c..b87b100c1378 100644
--- a/x/bank/keeper_test.go
+++ b/x/bank/internal/keeper/keeper_test.go
@@ -1,4 +1,4 @@
-package bank
+package keeper
 
 import (
 	"testing"
@@ -14,7 +14,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/store"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
-	"github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/types"
 	"github.com/cosmos/cosmos-sdk/x/params"
 )
 
@@ -120,13 +120,13 @@ func TestKeeper(t *testing.T) {
 	require.True(t, bankKeeper.GetCoins(ctx, addr2).IsEqual(sdk.NewCoins(sdk.NewInt64Coin("barcoin", 10), sdk.NewInt64Coin("foocoin", 8))))
 
 	inputs := []types.Input{
-		NewInput(addr, sdk.NewCoins(sdk.NewInt64Coin("foocoin", 3))),
+		types.NewInput(addr, sdk.NewCoins(sdk.NewInt64Coin("foocoin", 3))),
 		types.NewInput(addr2, sdk.NewCoins(sdk.NewInt64Coin("barcoin", 3), sdk.NewInt64Coin("foocoin", 2))),
 	}
 
 	outputs := []types.Output{
-		NewOutput(addr, sdk.NewCoins(sdk.NewInt64Coin("barcoin", 1))),
-		NewOutput(addr3, sdk.NewCoins(sdk.NewInt64Coin("barcoin", 2), sdk.NewInt64Coin("foocoin", 5))),
+		types.NewOutput(addr, sdk.NewCoins(sdk.NewInt64Coin("barcoin", 1))),
+		types.NewOutput(addr3, sdk.NewCoins(sdk.NewInt64Coin("barcoin", 2), sdk.NewInt64Coin("foocoin", 5))),
 	}
 	bankKeeper.InputOutputCoins(ctx, inputs, outputs)
 	require.True(t, bankKeeper.GetCoins(ctx, addr).IsEqual(sdk.NewCoins(sdk.NewInt64Coin("barcoin", 21), sdk.NewInt64Coin("foocoin", 4))))
@@ -139,7 +139,7 @@ func TestSendKeeper(t *testing.T) {
 	ctx := input.ctx
 	paramSpace := input.pk.Subspace(types.DefaultParamspace)
 	bankKeeper := NewBaseKeeper(input.ak, paramSpace, types.DefaultCodespace)
-	sendKeeper := NewBaseSendKeeper(input.ak, paramSpace, DefaultCodespace)
+	sendKeeper := NewBaseSendKeeper(input.ak, paramSpace, types.DefaultCodespace)
 	bankKeeper.SetSendEnabled(ctx, true)
 
 	addr := sdk.AccAddress([]byte("addr1"))
@@ -186,10 +186,10 @@ func TestSendKeeper(t *testing.T) {
 func TestViewKeeper(t *testing.T) {
 	input := setupTestInput()
 	ctx := input.ctx
-	paramSpace := input.pk.Subspace(DefaultParamspace)
-	bankKeeper := NewBaseKeeper(input.ak, paramSpace, DefaultCodespace)
+	paramSpace := input.pk.Subspace(types.DefaultParamspace)
+	bankKeeper := NewBaseKeeper(input.ak, paramSpace, types.DefaultCodespace)
 	bankKeeper.SetSendEnabled(ctx, true)
-	viewKeeper := NewBaseViewKeeper(input.ak, DefaultCodespace)
+	viewKeeper := NewBaseViewKeeper(input.ak, types.DefaultCodespace)
 
 	addr := sdk.AccAddress([]byte("addr1"))
 	acc := input.ak.NewAccountWithAddress(ctx, addr)
@@ -216,7 +216,7 @@ func TestVestingAccountSend(t *testing.T) {
 
 	origCoins := sdk.NewCoins(sdk.NewInt64Coin("stake", 100))
 	sendCoins := sdk.NewCoins(sdk.NewInt64Coin("stake", 50))
-	bankKeeper := NewBaseKeeper(input.ak, input.pk.Subspace(DefaultParamspace), DefaultCodespace)
+	bankKeeper := NewBaseKeeper(input.ak, input.pk.Subspace(types.DefaultParamspace), types.DefaultCodespace)
 	bankKeeper.SetSendEnabled(ctx, true)
 
 	addr1 := sdk.AccAddress([]byte("addr1"))
@@ -250,7 +250,7 @@ func TestVestingAccountReceive(t *testing.T) {
 
 	origCoins := sdk.NewCoins(sdk.NewInt64Coin("stake", 100))
 	sendCoins := sdk.NewCoins(sdk.NewInt64Coin("stake", 50))
-	bankKeeper := NewBaseKeeper(input.ak, input.pk.Subspace(DefaultParamspace), DefaultCodespace)
+	bankKeeper := NewBaseKeeper(input.ak, input.pk.Subspace(types.DefaultParamspace), types.DefaultCodespace)
 	bankKeeper.SetSendEnabled(ctx, true)
 
 	addr1 := sdk.AccAddress([]byte("addr1"))
@@ -284,7 +284,7 @@ func TestDelegateCoins(t *testing.T) {
 
 	origCoins := sdk.NewCoins(sdk.NewInt64Coin("stake", 100))
 	delCoins := sdk.NewCoins(sdk.NewInt64Coin("stake", 50))
-	bankKeeper := NewBaseKeeper(input.ak, input.pk.Subspace(DefaultParamspace), DefaultCodespace)
+	bankKeeper := NewBaseKeeper(input.ak, input.pk.Subspace(types.DefaultParamspace), types.DefaultCodespace)
 	bankKeeper.SetSendEnabled(ctx, true)
 
 	addr1 := sdk.AccAddress([]byte("addr1"))
@@ -321,7 +321,7 @@ func TestUndelegateCoins(t *testing.T) {
 
 	origCoins := sdk.NewCoins(sdk.NewInt64Coin("stake", 100))
 	delCoins := sdk.NewCoins(sdk.NewInt64Coin("stake", 50))
-	bankKeeper := NewBaseKeeper(input.ak, input.pk.Subspace(DefaultParamspace), DefaultCodespace)
+	bankKeeper := NewBaseKeeper(input.ak, input.pk.Subspace(types.DefaultParamspace), types.DefaultCodespace)
 	bankKeeper.SetSendEnabled(ctx, true)
 
 	addr1 := sdk.AccAddress([]byte("addr1"))
diff --git a/x/bank/types/codec.go b/x/bank/internal/types/codec.go
similarity index 100%
rename from x/bank/types/codec.go
rename to x/bank/internal/types/codec.go
diff --git a/x/bank/types/errors.go b/x/bank/internal/types/errors.go
similarity index 100%
rename from x/bank/types/errors.go
rename to x/bank/internal/types/errors.go
diff --git a/x/bank/types/key.go b/x/bank/internal/types/key.go
similarity index 100%
rename from x/bank/types/key.go
rename to x/bank/internal/types/key.go
diff --git a/x/bank/types/msgs.go b/x/bank/internal/types/msgs.go
similarity index 100%
rename from x/bank/types/msgs.go
rename to x/bank/internal/types/msgs.go
diff --git a/x/bank/types/msgs_test.go b/x/bank/internal/types/msgs_test.go
similarity index 100%
rename from x/bank/types/msgs_test.go
rename to x/bank/internal/types/msgs_test.go
diff --git a/x/bank/types/params.go b/x/bank/internal/types/params.go
similarity index 100%
rename from x/bank/types/params.go
rename to x/bank/internal/types/params.go
diff --git a/x/bank/tags/tags.go b/x/bank/internal/types/tags.go
similarity index 95%
rename from x/bank/tags/tags.go
rename to x/bank/internal/types/tags.go
index b4586818335c..9877d7591595 100644
--- a/x/bank/tags/tags.go
+++ b/x/bank/internal/types/tags.go
@@ -1,4 +1,4 @@
-package tags
+package types
 
 import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
diff --git a/x/bank/module.go b/x/bank/module.go
index 2499c2e9ab5e..eb0b85634800 100644
--- a/x/bank/module.go
+++ b/x/bank/module.go
@@ -15,7 +15,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/auth"
 	"github.com/cosmos/cosmos-sdk/x/bank/client/cli"
 	"github.com/cosmos/cosmos-sdk/x/bank/client/rest"
-	"github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/keeper"
 )
 
 var (
@@ -29,24 +29,20 @@ type AppModuleBasic struct{}
 var _ module.AppModuleBasic = AppModuleBasic{}
 
 // module name
-func (AppModuleBasic) Name() string {
-	return types.ModuleName
-}
+func (AppModuleBasic) Name() string { return ModuleName }
 
 // register module codec
-func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) {
-	types.RegisterCodec(cdc)
-}
+func (AppModuleBasic) RegisterCodec(cdc *codec.Codec) { RegisterCodec(cdc) }
 
 // default genesis state
 func (AppModuleBasic) DefaultGenesis() json.RawMessage {
-	return types.ModuleCdc.MustMarshalJSON(DefaultGenesisState())
+	return ModuleCdc.MustMarshalJSON(DefaultGenesisState())
 }
 
 // module validate genesis
 func (AppModuleBasic) ValidateGenesis(bz json.RawMessage) error {
 	var data GenesisState
-	err := types.ModuleCdc.UnmarshalJSON(bz, &data)
+	err := ModuleCdc.UnmarshalJSON(bz, &data)
 	if err != nil {
 		return err
 	}
@@ -84,24 +80,18 @@ func NewAppModule(keeper Keeper, accountKeeper auth.AccountKeeper) AppModule {
 }
 
 // module name
-func (AppModule) Name() string {
-	return types.ModuleName
-}
+func (AppModule) Name() string { return ModuleName }
 
 // register invariants
 func (am AppModule) RegisterInvariants(ir sdk.InvariantRegistry) {
-	RegisterInvariants(ir, am.accountKeeper)
+	keeper.RegisterInvariants(ir, am.accountKeeper)
 }
 
 // module message route name
-func (AppModule) Route() string {
-	return types.RouterKey
-}
+func (AppModule) Route() string { return RouterKey }
 
 // module handler
-func (am AppModule) NewHandler() sdk.Handler {
-	return NewHandler(am.keeper)
-}
+func (am AppModule) NewHandler() sdk.Handler { return NewHandler(am.keeper) }
 
 // module querier route name
 func (AppModule) QuerierRoute() string { return "" }
@@ -112,7 +102,7 @@ func (AppModule) NewQuerierHandler() sdk.Querier { return nil }
 // module init-genesis
 func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.ValidatorUpdate {
 	var genesisState GenesisState
-	types.ModuleCdc.MustUnmarshalJSON(data, &genesisState)
+	ModuleCdc.MustUnmarshalJSON(data, &genesisState)
 	InitGenesis(ctx, am.keeper, genesisState)
 	return []abci.ValidatorUpdate{}
 }
@@ -120,7 +110,7 @@ func (am AppModule) InitGenesis(ctx sdk.Context, data json.RawMessage) []abci.Va
 // module export genesis
 func (am AppModule) ExportGenesis(ctx sdk.Context) json.RawMessage {
 	gs := ExportGenesis(ctx, am.keeper)
-	return types.ModuleCdc.MustMarshalJSON(gs)
+	return ModuleCdc.MustMarshalJSON(gs)
 }
 
 // module begin-block
diff --git a/x/bank/simulation/msgs.go b/x/bank/simulation.go
similarity index 88%
rename from x/bank/simulation/msgs.go
rename to x/bank/simulation.go
index 327bee2e2fb6..3fe611a9d067 100644
--- a/x/bank/simulation/msgs.go
+++ b/x/bank/simulation.go
@@ -1,4 +1,4 @@
-package simulation
+package bank
 
 import (
 	"fmt"
@@ -9,15 +9,16 @@ import (
 	"github.com/cosmos/cosmos-sdk/baseapp"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
-	"github.com/cosmos/cosmos-sdk/x/bank"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/keeper"
+	"github.com/cosmos/cosmos-sdk/x/bank/internal/types"
 	"github.com/cosmos/cosmos-sdk/x/mock"
 	"github.com/cosmos/cosmos-sdk/x/simulation"
 )
 
 // SendTx tests and runs a single msg send where both
 // accounts already exist.
-func SimulateMsgSend(mapper auth.AccountKeeper, bk bank.Keeper) simulation.Operation {
-	handler := bank.NewHandler(bk)
+func SimulateMsgSend(mapper auth.AccountKeeper, bk keeper.Keeper) simulation.Operation {
+	handler := NewHandler(bk)
 	return func(r *rand.Rand, app *baseapp.BaseApp, ctx sdk.Context, accs []simulation.Account) (
 		opMsg simulation.OperationMsg, fOps []simulation.FutureOperation, err error) {
 
@@ -35,7 +36,7 @@ func SimulateMsgSend(mapper auth.AccountKeeper, bk bank.Keeper) simulation.Opera
 }
 
 func createMsgSend(r *rand.Rand, ctx sdk.Context, accs []simulation.Account, mapper auth.AccountKeeper) (
-	fromAcc simulation.Account, comment string, msg bank.MsgSend, ok bool) {
+	fromAcc simulation.Account, comment string, msg types.MsgSend, ok bool) {
 
 	fromAcc = simulation.RandomAcc(r, accs)
 	toAcc := simulation.RandomAcc(r, accs)
@@ -59,12 +60,12 @@ func createMsgSend(r *rand.Rand, ctx sdk.Context, accs []simulation.Account, map
 	}
 
 	coins := sdk.Coins{sdk.NewCoin(initFromCoins[denomIndex].Denom, amt)}
-	msg = bank.NewMsgSend(fromAcc.Address, toAcc.Address, coins)
+	msg = types.NewMsgSend(fromAcc.Address, toAcc.Address, coins)
 	return fromAcc, "", msg, true
 }
 
 // Sends and verifies the transition of a msg send.
-func sendAndVerifyMsgSend(app *baseapp.BaseApp, mapper auth.AccountKeeper, msg bank.MsgSend, ctx sdk.Context, privkeys []crypto.PrivKey, handler sdk.Handler) error {
+func sendAndVerifyMsgSend(app *baseapp.BaseApp, mapper auth.AccountKeeper, msg types.MsgSend, ctx sdk.Context, privkeys []crypto.PrivKey, handler sdk.Handler) error {
 	fromAcc := mapper.GetAccount(ctx, msg.FromAddress)
 	AccountNumbers := []uint64{fromAcc.GetAccountNumber()}
 	SequenceNumbers := []uint64{fromAcc.GetSequence()}
@@ -76,7 +77,7 @@ func sendAndVerifyMsgSend(app *baseapp.BaseApp, mapper auth.AccountKeeper, msg b
 	if handler != nil {
 		res := handler(ctx, msg)
 		if !res.IsOK() {
-			if res.Code == bank.CodeSendDisabled {
+			if res.Code == types.CodeSendDisabled {
 				return nil
 			}
 			// TODO: Do this in a more 'canonical' way
@@ -110,8 +111,8 @@ func sendAndVerifyMsgSend(app *baseapp.BaseApp, mapper auth.AccountKeeper, msg b
 
 // SingleInputSendMsg tests and runs a single msg multisend, with one input and one output, where both
 // accounts already exist.
-func SimulateSingleInputMsgMultiSend(mapper auth.AccountKeeper, bk bank.Keeper) simulation.Operation {
-	handler := bank.NewHandler(bk)
+func SimulateSingleInputMsgMultiSend(mapper auth.AccountKeeper, bk keeper.Keeper) simulation.Operation {
+	handler := NewHandler(bk)
 	return func(r *rand.Rand, app *baseapp.BaseApp, ctx sdk.Context, accs []simulation.Account) (
 		opMsg simulation.OperationMsg, fOps []simulation.FutureOperation, err error) {
 
@@ -129,7 +130,7 @@ func SimulateSingleInputMsgMultiSend(mapper auth.AccountKeeper, bk bank.Keeper)
 }
 
 func createSingleInputMsgMultiSend(r *rand.Rand, ctx sdk.Context, accs []simulation.Account, mapper auth.AccountKeeper) (
-	fromAcc simulation.Account, comment string, msg bank.MsgMultiSend, ok bool) {
+	fromAcc simulation.Account, comment string, msg types.MsgMultiSend, ok bool) {
 
 	fromAcc = simulation.RandomAcc(r, accs)
 	toAcc := simulation.RandomAcc(r, accs)
@@ -154,16 +155,16 @@ func createSingleInputMsgMultiSend(r *rand.Rand, ctx sdk.Context, accs []simulat
 	}
 
 	coins := sdk.Coins{sdk.NewCoin(initFromCoins[denomIndex].Denom, amt)}
-	msg = bank.MsgMultiSend{
-		Inputs:  []bank.Input{bank.NewInput(fromAcc.Address, coins)},
-		Outputs: []bank.Output{bank.NewOutput(toAddr, coins)},
+	msg = types.MsgMultiSend{
+		Inputs:  []types.Input{types.NewInput(fromAcc.Address, coins)},
+		Outputs: []types.Output{types.NewOutput(toAddr, coins)},
 	}
 	return fromAcc, "", msg, true
 }
 
 // Sends and verifies the transition of a msg multisend. This fails if there are repeated inputs or outputs
 // pass in handler as nil to handle txs, otherwise handle msgs
-func sendAndVerifyMsgMultiSend(app *baseapp.BaseApp, mapper auth.AccountKeeper, msg bank.MsgMultiSend,
+func sendAndVerifyMsgMultiSend(app *baseapp.BaseApp, mapper auth.AccountKeeper, msg types.MsgMultiSend,
 	ctx sdk.Context, privkeys []crypto.PrivKey, handler sdk.Handler) error {
 
 	initialInputAddrCoins := make([]sdk.Coins, len(msg.Inputs))
@@ -184,7 +185,7 @@ func sendAndVerifyMsgMultiSend(app *baseapp.BaseApp, mapper auth.AccountKeeper,
 	if handler != nil {
 		res := handler(ctx, msg)
 		if !res.IsOK() {
-			if res.Code == bank.CodeSendDisabled {
+			if res.Code == types.CodeSendDisabled {
 				return nil
 			}
 			// TODO: Do this in a more 'canonical' way