80% of Native Americans died off from some sort of Pandemic before Europeans even arrived. Many of the Eastern tribes left for the West. The Blackfeet were apparently Eastern Algonquin originally.
When they left, they left many sizeable wooden cities behind. This is why plains Indians were Nomadic and lived in tents. They feared (rightly) that living in cities could be unhealthy.
One of the most interesting things I learned in college in the 80s was initially the English settlers did not build forts. They moved into abandoned Native cities of wood that the indigenous tribes left behind.
My grandpa's family left the Blackfoot Rez in Montana after WW1. We visited that Rez in 72. His cousins teased him about getting their land in WV back.
