Final answer:
Seas and deserts act as natural barriers due to the physical obstacles they create. In Mesopotamia, the location of seas and deserts was different as it was between the Tigris and Euphrates rivers, which provided abundant water and led to the development of urban centers.
Step-by-step explanation:
Seas and deserts act as natural barriers because they create physical obstacles that are difficult to overcome. For example, deserts like the Sahara in Africa or the Gobi in Asia are vast and have harsh climates, making them difficult to cross. Similarly, seas like the Atlantic or Pacific ocean are large bodies of water that require transportation or navigation skills to cross. In Mesopotamia, the location of seas and deserts differed as it was a region located between the Tigris and Euphrates rivers, which provided abundant water for agriculture. The rivers' unpredictable flooding required the residents to build hydrological systems for protection, which led to the development of large-scale settlements and urban centers.