Since when do people know about the time zones?

by vaynemainhere

What I mean is since the fastest way to travel back then was riding horses (and it's not that fast), were people aware that it's night time on the other side of the planet? Considering they didn't even know the earth is round for sure, I can't see how they might realise this. When was the first time someone mentioned this subject ? Did ancient greeks or egyptians know this ? Thanks!

Iphikrates

There are some useful answers to this in the FAQ, for instance by /u/jschooltiger and /u/restricteddata here.