Legal gatekeepers invented Blackness as property to justify enslavement.

Evidence

The same formula was used in the earliest and middle passages of American slavery. Because indigenous peoples were thought to be too “unruly” to serve as slaves and white indentured servants became too costly, the American appetite for cheap labor turned to the westernmost regions of Africa for human capital. To justify African enslavement, legal gatekeepers invented “Blackness” as a category that branded all Africans as property to be sold and owned, a classification oriented against whiteness, its “superior opposite.” — Khaled A. Beydoun, The New Crusades_ Islamophobia and the…, 218