diff --git a/service/history/nDCHistoryReplicator.go b/service/history/nDCHistoryReplicator.go
index 0429761ed71..5d0e4c2c6e8 100644
--- a/service/history/nDCHistoryReplicator.go
+++ b/service/history/nDCHistoryReplicator.go
@@ -866,18 +866,17 @@ func (r *nDCHistoryReplicatorImpl) backfillHistory(
 		lastEventID,
 		lastEventVersion),
 	)
-	var lastHistoryBatch *commonpb.DataBlob
-	prevTxnID := common.EmptyVersion
 	historyBranch, err := serialization.HistoryBranchFromBlob(branchToken, enumspb.ENCODING_TYPE_PROTO3.String())
 	if err != nil {
 		return nil, err
 	}
-	latestBranchID := historyBranch.GetBranchId()
-	var prevBranchID string
 
-	sortedAncestors := copyAndSortAncestors(historyBranch.GetAncestors())
+	prevTxnID := common.EmptyVersion
+	var lastHistoryBatch *commonpb.DataBlob
+	var prevBranchID string
+	sortedAncestors := sortAncestors(historyBranch.GetAncestors())
 	sortedAncestorsIdx := 0
-	historyBranch.Ancestors = nil
+	var ancestors []*persistencespb.HistoryBranchRange
 
 BackfillLoop:
 	for remoteHistoryIterator.HasNext() {
@@ -891,17 +890,18 @@ BackfillLoop:
 			continue BackfillLoop
 		}
 
+		branchID := historyBranch.GetBranchId()
 		if sortedAncestorsIdx < len(sortedAncestors) {
 			currentAncestor := sortedAncestors[sortedAncestorsIdx]
 			if historyBlob.nodeID >= currentAncestor.GetEndNodeId() {
 				// update ancestor
-				historyBranch.Ancestors = append(historyBranch.Ancestors, currentAncestor)
+				ancestors = append(ancestors, currentAncestor)
 				sortedAncestorsIdx++
 			}
 			if sortedAncestorsIdx < len(sortedAncestors) {
 				// use ancestor branch id
 				currentAncestor = sortedAncestors[sortedAncestorsIdx]
-				historyBranch.BranchId = currentAncestor.GetBranchId()
+				branchID = currentAncestor.GetBranchId()
 				if historyBlob.nodeID < currentAncestor.GetBeginNodeId() || historyBlob.nodeID >= currentAncestor.GetEndNodeId() {
 					return nil, serviceerror.NewInternal(
 						fmt.Sprintf("The backfill history blob node id %d is not in acestoer range [%d, %d]",
@@ -910,13 +910,14 @@ BackfillLoop:
 							currentAncestor.GetEndNodeId()),
 					)
 				}
-			} else {
-				// no more ancestor, use the latest branch ID
-				historyBranch.BranchId = latestBranchID
 			}
 		}
 
-		filteredHistoryBranch, err := serialization.HistoryBranchToBlob(historyBranch)
+		filteredHistoryBranch, err := serialization.HistoryBranchToBlob(&persistencespb.HistoryBranch{
+			TreeId:    historyBranch.GetTreeId(),
+			BranchId:  branchID,
+			Ancestors: ancestors,
+		})
 		if err != nil {
 			return nil, err
 		}
@@ -926,7 +927,7 @@ BackfillLoop:
 		}
 		_, err = r.shard.GetExecutionManager().AppendRawHistoryNodes(ctx, &persistence.AppendRawHistoryNodesRequest{
 			ShardID:           r.shard.GetShardID(),
-			IsNewBranch:       prevBranchID != historyBranch.BranchId,
+			IsNewBranch:       prevBranchID != branchID,
 			BranchToken:       filteredHistoryBranch.GetData(),
 			History:           historyBlob.rawHistory,
 			PrevTransactionID: prevTxnID,
@@ -942,7 +943,7 @@ BackfillLoop:
 			return nil, err
 		}
 		prevTxnID = txnID
-		prevBranchID = historyBranch.BranchId
+		prevBranchID = branchID
 		lastHistoryBatch = historyBlob.rawHistory
 	}
 
@@ -954,9 +955,7 @@ BackfillLoop:
 	return lastEventTime, nil
 }
 
-func copyAndSortAncestors(input []*persistencespb.HistoryBranchRange) []*persistencespb.HistoryBranchRange {
-	ans := make([]*persistencespb.HistoryBranchRange, len(input))
-	copy(ans, input)
+func sortAncestors(ans []*persistencespb.HistoryBranchRange) []*persistencespb.HistoryBranchRange {
 	if len(ans) > 0 {
 		// sort ans based onf EndNodeID so that we can set BeginNodeID
 		sort.Slice(ans, func(i, j int) bool { return ans[i].GetEndNodeId() < ans[j].GetEndNodeId() })