diff --git a/backend/packages/identity-scan/src/scripts/known/save.js b/backend/packages/identity-scan/src/scripts/known/save.js
new file mode 100644
index 000000000..59eb620f9
--- /dev/null
+++ b/backend/packages/identity-scan/src/scripts/known/save.js
@@ -0,0 +1,43 @@
+const { peopleChainName } = require("../../scan/common/consts");
+const {
+  mongo: {
+    known: { saveKnownHeights },
+  },
+} = require("@osn/scan-common");
+
+async function saveHeightsCommon(col) {
+  const items = await col.find({}).toArray();
+  const heights = [];
+  const peopleChainHeights = [];
+
+  for (const item of items) {
+    if (item.indexer) {
+      const { chain, blockHeight } = item.indexer;
+      if (peopleChainName === chain) {
+        peopleChainHeights.push(blockHeight);
+      } else {
+        heights.push(blockHeight);
+      }
+    }
+
+    if (item.timeline) {
+      for (const timelineItem of item.timeline || []) {
+        if (timelineItem.indexer) {
+          const { chain, blockHeight } = item.indexer;
+          if (peopleChainName === chain) {
+            peopleChainHeights.push(blockHeight);
+          } else {
+            heights.push(blockHeight);
+          }
+        }
+      }
+    }
+  }
+
+  const uniqueHeights = [...new Set(heights)];
+  await saveKnownHeights(uniqueHeights);
+
+  const uniquePeopleChainHeights = [...new Set(peopleChainHeights)];
+  console.log(uniquePeopleChainHeights);
+  // todo: save people chain heights
+}