Probably the main reason africans rather than native americans became slaves in america was that

answer:

it caused mass african migration, african populations to grow, african empires to topple, and racism against slaves to emerge.

possible the invasion of room could have been avodiable but the people of rome were to stubboron and to wealthy the kingdoms saw them as a threat if they dialred it downa   bit ten i dont think they wouldnt failed   china was not iacvvdoaible they caused war to much and were out of hand therefor that must have happened india i dont really know it could of