The Kush Kingdom was settled around the Nile, it's NOT sub-saharan Africa.

And yes, there are a lot of historical artifacts spread out in the world. But how much WRITTEN and RECORDED history can you find? You can find a totem buried somewhere in the south of Argentina, so you know you had an advanced culture there. But can you name them? Does it have the ruler's name?

Nobody is arguing that there were advanced civilizations ASIDE from Mesopotamia, China and North Africa. But we have very little written records to name them, classify them, etc.