Final answer:
All Native Americans are traditionally believed to be descendants of people who migrated from Asia via the Bering Land Bridge. This migration occurred during the last ice age, and was followed later by some groups also traveling by sea along the Pacific coast.
Step-by-step explanation:
Traditional theory posits that all Native Americans are descendants of people who migrated from Asia to the Americas. The most widely accepted explanation is the Bering Land Bridge migration model, which suggests that during the last ice age, humans crossed what is now known as the Bering Strait, which was then a land bridge connecting Siberia to Alaska due to lower sea levels.
This migration is believed to have occurred in at least four waves, following mammoths, mastodons, and other megafauna, with the first groups crossing approximately 15,000 years ago. Over time, these peoples spread southward, eventually populating both North and South America and giving rise to diverse indigenous cultures.
In addition to the land bridge migration, the coastal migration theory suggests that some groups also traveled by sea along the Pacific coast to reach South America. Both theories are supported by genetic, archaeological, and linguistic evidence, indicating a long span of human migration over land and by sea.