Why did plains indians lose their battle to keep their land and their way of life?

2686-2181 bce-- "egyptian civilization developed along the nile river in large part because the river’s annual flooding ensured reliable, rich soil for growing crops."

1069-664 bce-- "ancient egyptians developed wide-reaching trade networks along the nile, in the red sea, and in the near east."

i think the answer is the one about environmental and social health.

hope this