Did violence and mistreatment of African Americans accelerate or limit the Great Migration?

Which colony did the first mass influx of slaves populate?

Did the spanish settlers and missions have a positive effect on world history? why, what did they do that was positive? why was the treaty of paris (1763) good for the world/world history? did the plymouth colony have a positive effect on world history? why, what did they do that was positive?

Why might the greeck city states have an advantage over the persians