Graeber and Wengrow contest that take severely with their survey of modern anthro and archaeological research, I recommend their papers or Dawn of Everything
Maybe the peoples in earlier times were simply less willing to put up with being bullied and exploited. Relatively low numbers and abundant unsettled land gave them more options that many humans have had since. The Nile watershed was a wonder of ancient agricultural engineering: it was also the largest slave society up to that point in history.