In my semi-regular survey of origin stories published by innerboob, I recently came across a podcast interview with a historian who specialized in US slave trade. (When I relocate the link, I'll post it here.) iirc, The occasion for the interview is a Pulitzer Prize for the latest research into the origin of "white supremacy." The historian nailed the deed to a specific 15th century Portuguese document.

Now, the thesis of periodicity --before | discovery| after-- and instrumentality of "race" relationships that he develops from that seems to me to pertain also today to recurring, opportune discoveries of oppressed ethnic minorities such as The Ahwaz within a hegemonic "evil" (Greater Middle East<->Persians<->Medi) upon which racists operate. The historian, intentionally or not, seems to me to postulate a cognitive function in race schema that is systematically associated with value discovery. I paraphrase from memory.

BEFORE: ethnic heterogeneity within a population identified by geography
DISCOVERY: object permanence
AFTER: undifferentiated identity of a population by geography ("blacks", "whites")

Diversity is the key to economic and political evolution.