Some savvy West African tribal leaders 400 years ago who decided to offload their violent criminals and captured invaders onto the slave trade. A win-win for them.
The Dumms have been trying to kill off the blacks since then and have succeeded only in dropping their numbers from 13% down to 7% percent of the actual number of people in the US including non-citizens, but mostly by importing Hispanics and making baby parts a fungible commodity.
They've even found s genetic mutation that is carried by American blacks at a much higher rate than the African blacks who now occupy the old home range. It has been identified as coming from black African ancestors and is correlated with violent behavior.