Where were pants made?

Pants are, and were, made all over the world. If you mean where was the first pair of pants made... no one knows because they were first made before recorded history. ... Possibly Siberia (see related link).

I imagine that it happened something like this:

caveman joe: boy, am i cold. sitting under this pile of furs is warmer, but wouldn't it be cool if i could be warm while walking around?

caveman betty: that would be cool... hmm. >sew sew sew< ... here, have a skirt.

caveman joe: this is okay, but really drafty, and i am still cold. you wear it. i want something better.

caveman betty: <grumble> >sew sew sew< here. i split it so that it will cover your legs individually. ...might be a little tight at the crotch.

caveman joe: nice. warmer. yes, tight. you did that on purpose. but warmer. i will wear anyway.