Why were two southern colonies initially resistant to slavery?
Slavery didn’t begin in the South. Slavery was brought into the South whenever the South became the nation’s work-horse. Since the “founders and first occupants” of this great land failed at enslaving enough Native Americans, and failed at enslaving poor Europeans, they bought slaves from Africa. I’m not sure what “southern colonies” you’re speaking of nor do I know what time frame you’re speaking of. The first African slaves were brought to this country in 1619. Prior to (and after) that there were Native American and European slaves. So, you’d really need to provide more information.