Final answer:
The Sumerian city-states were isolated and independent due to geographic barriers, political disagreements, economic competition, and cultural differences.
Step-by-step explanation:
The Sumerian city-states were isolated and independent from each other due to a combination of factors. The first factor was geographic barriers, such as rivers and marshlands, which created natural boundaries and resulted in the isolation of each city-state.
Secondly, there were political disagreements and power struggles among city-state rulers, leading to a lack of unity and collaboration. Additionally, there was economic competition for resources, particularly fertile land, which led to a desire for independence and autonomy.
Lastly, cultural differences and distinct religious practices also contributed to the separation and independence of Sumerian city-states.