[gcruse]

For millenia (as far as we have records, starting with schools in ancient China - Confucius comes to mind) mankind educated its offspring without any specific diversity education.

LOL  And we know how diverse China was.   Not.

[GSlob]

It is simply that still earlier educational records (Sumerian cuneiform pottery shards and Egyptian papyri from their corresponding schools) are too fragmentary to present a coherent picture. Confucian China is the earliest society which left a reasonably complete educational record of itself. Greeks and Romans chronologically came a tad behind. Their societies contained much more than "outer barbarians, bearing tribute" or "owing tribute, but not bearing it". They, too, did not practice diversity education, for they did not need it.