Conversation so far:
what can you tell me about the early history of blackfoot?
The Niitsitapi, also known as the Blackfoot or Blackfeet Indians, reside in the Great Plains of Montana and the Canadian provinces of Alberta and Saskatchewan.
when did they reside in the great plains?
By 1200.
what else did they do in those years?
Due to language and cultural patterns, anthropologists believe the Niitsitapi did not originate in the Great Plains of the Midwest North America, but migrated.

Question: where did they migrated from?
Self-contained rewrite: Where did the Niitsitapi migrate from?