Well ancient Greece was an oligarchy (kind of like a democracy). Greece has City States, as well as Ancient Mesopotamia. Mesopotamia had kings though, but was ran like an Oligarchy.
The exchange that most affected the indigenous people was the one of diseases. Native Americans hadn't encounter the diseases the European brought before, so they hadn't develop immunity to them. This is the major reason of the large death of Native Americans, besides the war between them and the brutality of the Europeans.
He abolished slavery and started the civil war
