The concept of race as understood in modern terms largely developed after the beginning of the trans-Atlantic slave trade, which initially did not base enslavement on race.
When you consider race didn’t exist yet when the slave trade started.

The slave trade didn’t come out of nowhere
Source: reparationscomm.org
Key Evidence
Slavery existed globally before the trans-Atlantic trade but was not based on race.
ldhi.library.cofc.eduldhi.library.cofc.eduSlavery before the Trans-Atlantic Trade · African Passages, Lowcountry...
nytimes.comnytimes.comA Brief History of Slavery That You Didn't Learn in School
The modern racial concept emerged mainly in the 15th century with European expansion and was used to justify African enslavement.
quora.comquora.comIs it true that the modern idea of race wasn't invented until the African slave...
nmaahc.si.edunmaahc.si.eduHistorical Foundations of Race
Earlier societies had notions of group difference but lacked formal racial classifications.
quora.comquora.comIs it true that the modern idea of race wasn't invented until the African slave...
Racial ideology linked to slavery is a constructed concept tied to economic motives during the slave trade era.
reparationscomm.orgreparationscomm.orgThe slave trade didn’t come out of nowhere
What the Evidence Shows
Historical evidence shows that various forms of slavery existed long before the trans-Atlantic slave trade, but these earlier systems were generally not based on racial categories.ldhi.library.cofc.eduldhi.library.cofc.eduSlavery before the Trans-Atlantic Trade · African Passages, Lowcountry...
nytimes.comnytimes.comA Brief History of Slavery That You Didn't Learn in School Enslavement was often related to war captives, debt, or social status rather than race.
The modern idea of race, particularly as a rigid classification system used to justify slavery and colonialism, emerged primarily in the 15th century and later, coinciding with European expansion and the trans-Atlantic slave trade.quora.comquora.comIs it true that the modern idea of race wasn't invented until the African slave...
nmaahc.si.edunmaahc.si.eduHistorical Foundations of Race+1 more This racial categorization was constructed to rationalize the enslavement of Africans.
Prior to this period, many societies recognized differences among peoples but did not conceptualize these differences in the fixed racial terms that developed later. For example, ancient civilizations had notions of cultural or ethnic superiority but not a formalized racial hierarchy.quora.comquora.comIs it true that the modern idea of race wasn't invented until the African slave...
Some sources note that while racism as a broader phenomenon might have existed in various forms before US slavery or the trans-Atlantic trade, the specific racial ideology tied to African enslavement was a later development.thehill.comthehill.comWould racism exist if there had been no US slavery?
The emergence of race as a concept is thus closely linked to economic and social systems that required justification for enslaving particular groups, especially Africans during the trans-Atlantic slave trade.reparationscomm.orgreparationscomm.orgThe slave trade didn’t come out of nowhere
In summary, while human distinctions and prejudices existed historically, the modern concept of race as a justification for slavery did not exist at the start of the trans-Atlantic slave trade but developed alongside it.