It’s deliberately vague, and there’s a lot of authorial leeway due to that screening off of all but the most recent history in the setting. The continents correspond and the humans are indistinguishable on casual observation from Earth humans physically, medically, and behaviourally, so it should be some sort of alternate history Earth. Whether any divergence is 200 or 20k years ago is hard to say (and Eliezer may not yet have decided).
It’s deliberately vague, and there’s a lot of authorial leeway due to that screening off of all but the most recent history in the setting. The continents correspond and the humans are indistinguishable on casual observation from Earth humans physically, medically, and behaviourally, so it should be some sort of alternate history Earth. Whether any divergence is 200 or 20k years ago is hard to say (and Eliezer may not yet have decided).