How did physical geography Sumer leave its cities unprotected?

Answer 1

Sumer's physical geography, characterized by flat, open plains and the absence of natural barriers like mountains or dense forests, left its cities vulnerable to invasion. The region was also crisscrossed by rivers, which facilitated trade but made it easier for potential attackers to approach. Additionally, the lack of fortifications in earlier city-states meant that Sumerian cities were exposed to external threats, often leading to conflicts with neighboring regions.