You, the Boneman for sure, and others need to enroll in a local community college and take some history classes.
It is not obvious. Most slavery in history was not race based as there was no such thing as the concept of different races of humans. The concept of the different races of humans did not come until the racist Europeans in 16,17 centuries came up with the concept of caucasian, negroid, and mongloid(Asian) races. The racist European so-called scientists measured skulls and published false findings that since the skulls of caucasians were larger than the skulls of the negroids, that caucasians were more intelligent.
Out of all of that chattel or race based slavery was born along with the transatlantic slave trade. Chattel slavery is where the enslaved is property of the owner for life or until sold to someone like property. Most of the enslaved during the transatlantic slave trade were Africans. They went to the Americas including the US, Caribbean and South America.