Why was Mesopotamia easy to invade

Mesopotamia was susceptible to invasion because it was located in such a vulnerable, open area. There were no mountains surrounding it from invaders, so enemies could easily get in the great empires that thrived off of the very fertile land. Many people wanted to invade because of the fertile land and easy access to the Tigris and Euphrates Rivers.
Hope it  helped!           :()

The one that most represents the earths mantle would be the skin since the mantle is the upper part of the earths depths which is just like the skin of an apple.