Question

Score: Who am I? "Not to brag, but I was only the third king in history to create an empire. I conquered states throughout Mesopotamia, from the Mediterranean Sea to the Black Sea. Unfortunately, empires as big as mine are hard to control. Citizens ended up revolting and I was pushed out of power by the Sumerians."

Answer 1

The answer you're looking for would be Sargon of Akkad, also known as Sargon the Great. For him it was considered that he was the third king to create an empire and conquer states throughout Mesopotamia. 

Answer 2

The person behind the facts stated in the question is Sargon the Great. He was the third king in history to create an empire, as he was the first ruler of the Semitic-speaking Akkadian Empire. He was famous for his conquests of the Sumerian city-states including Mesotopotamia and parts of Iran, Turkey and Syria. Sargon was detroned by the Sumerians as a result of a revolution.