Question

Why was Mesopotamia know as the land between 2 rivers

Answer 1

Because it was between Tigris and Euphrates

Answer 2

Because that was literally what Mesopotamia was.

The two rivers that surrounded Mesopotamia with the Tigris and the Euphrates, giving the land itself fertile soil and it became known as the Fertile Crescent as well.

But, in short, Mesopotamia was known as the land between two rivers because it was located between the Tigris and Euphrates - two rivers.

Hope this helps!