In mesopotamia, the early city states were between the tigris and the

The early city states in Mesopotamia were between Tigris and Euphrates.

The Tigris is where it has two great rivers of the eastern member in which they are responsible of defining Mesopotamia whereas is the river that is longest and considered to be most important to the Western Asia in which Tigris is also considered to be historically important as both defines Mesopotamia. 

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