First they would have to be in a anti slavery state, there were also some wealthy African Americans in the time of slavery
Nabopolassar led the final revolt against Assyria that would topple their empire. He was a general in the Babylonian army, and he commanded his forces against the Assyrian rulers.
It led for the citizens of each state to decide whether or not their state would be a free or slave state. Although it did backfire with events such as bleeding Kansas
1. The empires are gone 2. The wars over religion and territory have stopped 3. Population has skyrocketed