The correct answer to this open question is the following.
The geographic feature of Mesopotamia that led to the Sumerians being easily taken over was the Tigris and Euphrates Rivers that made it easy for their enemies to navigate and invade them.
Sumeria was the oldest civilization known to man. Sumerians settled in the middle of the Tigris and Euphrates Rivers in the Middle East region. There, they developed agriculture techniques and learn how to use the flood of the rivers to grow crops in that fertile soil. That is how they prosper for some time until their enemies could access their city-states navigating through both rivers.
The correct answer is Canada.
While some went to the United Kingdom after the war, many took boats out of American cities and ended up in Halifax, now in Nova Scotia, before spreading out throughout what is today Canada.