How Muslims believed earth was spherical long before anybody mentions it.

[Regina]

It might be hard to judge this since we're living in a world where we now know it's round. However, to me it seems almost like common sense that it's round even to primitive man that had no scientific knowledge.

I mean, when the sun sets, you can still see tall trees and high hills/cliffs being illuminated by sunlight for longer than the ground. That wouldn't happen so dramatically if the Earth is flat. That's probably how the Egyptians first recognised it, by noticing that the sun sets "later" if you're standing at the top of the pyramids than if you're standing on the ground next to the pyramids.

If you think about China as well, that was a civilisation with extensive latitudinal range, even from a very early point in history. They would have wanted an explanation as to why it was generally warmer in the southern part of their lands than it is in the North. Sure, at face value that doesn't necessarily mean the Earth is round, but do some investigating and it's not a hard hypothesis to fall upon.