Answer:
The Sumerians' Amorite Wall
During the 21st century B.C., the ancient Sumerian rulers Shulgi and Shu-Sin constructed a massive fortified barrier to keep out the Amorites, a group of nomadic tribesmen who had been making incursions into Mesopotamia.
AND
Walls were considered the key to peace. Four thousand years ago, the Mesopotamian king Shulgi, builder of the first known border wall, wrote that his fortifications would finally allow the people to rest in peaceful dwelling places.
Explanation:
