I’m really enjoying both series of Western Civilization!
One question that I’ve always had, is the how/when/why did people migrate to the Americas in the first place? It seems most likely that they would have gone northeast to the Russia/Alaska area, but for what reason? It gets colder the more north you go, so I don’t know why people would want to migrate to an even colder environment. Did they cross the ocean to get to Alaska? Was it it solid ice? Was the sea level lower, and there was dry land linking the two together? How did they know there was even land in that direction in the first place? Also, when did all this happen? How long does it take for people to migrate all the way across the world setting up cultures all the way to South America?
The discipline of history, because of its reliance on written testimony, isn’t really equipped to answer your questions. They fall more under the purview of archeology.
There are multiple theories as to how, when, and why people first came to the Americas. The one that seems to be most in favor right now is that they crossed a land bridge from Russia to Alaska in pursuit of big game during an Ice Age some 12,000 years ago. But any explanation involves a decent dose of speculation.
There is another, more plausible in my thinking, theory. The Book of Mormon is a record of the inhabitants of ancient America. It includes the history of two separate sets of people. The first set, recorded in the Book of Either, were led out of the east by a prophet. They came by boat, or barges, constructed after revelation. This was at the time of the Tower of Babel, so after Noah and before Abraham. They destroyed themselves, one man surviving to see the second set inherit the Americas.
The second set of people were also lead out of the east by revelation. They also came by boat. They left Jerusalem a few years before the Babylonian captivity, in the first year of King Zedekiah, King of Judah (The rest of the books in the Book of Mormon cover their history (600BC to 400AD).