Answer:
D. controlling such a large area
Explanation:
The area that's controlled by the Mesopotamian empires covered western Asia and Northern part of Africa. In 4000 BCE This was among the largest empires in the world .
Since there was no effective method of long distance communication during that time, managing this very large are was extremely difficult. In the end, many part of their regions were left unmanaged and fall to the attacks from other smaller empires or groups of barbarians.
