What did the flooding of the Tigris and Euphrates rivers led to an abundance of?

The flooding of the Tigris and Euphrates rivers led to an abundance of fertile soil, which was crucial for agriculture in ancient Mesopotamia. This seasonal inundation deposited nutrient-rich silt on the land, allowing for the cultivation of staple crops like barley and wheat. Consequently, this agricultural surplus supported the growth of cities and complex societies in the region, facilitating advancements in trade, culture, and governance.