Which event in history most affected native americans?

Why did leaders such as siddhartha gautama abandon hinduism to createbuddhism around 500 bce:

If one thinks illegal immigrants should become american citizens, should they become american citizens automatically or should there be a waiting period? if there should be a waiting period, explain why.

Prior to the presence of europeans on the continent, the slave trade in africa a) did not exist in any form. b) was limited to internal trade only. c) included the trans-saharan and indian ocean slave trade. d) was rarely needed due to the lack of an agricultural economy.