Question

What was the most commonly accepted theory of the Indian origin in North American?

Answer 1

Native Americans ("Indians") migrated from Siberia across the Bering Strait, which during the last ice age was dry land. The exact time period isn't known (I believe the most commonly accepted date is about 10,000 years ago). Also, there were probably multiple migrations (at least three) based on linguists' analysis of current native American languages.

Answer 2

Migrated across a land bridge from Russia to Alaska.

This common belief has been challenged in recent years with more archaeological information coming from South America showing ruins older than any in North America. There are some historians who believe people may have come by boat and settled the land before the migration across the land bridge.

hope that i helped :)