Answer:
The three most important rivers areThe Indus River, the Gangus River and the Brahmaputra River.
I would say the Tigris, Euphrates, and the Indus River (though some might argue that the Jordan River was more important).
The Tigris and Euphrates provided Mesopotamia with water and soil, allowing them to develop agriculture using irrigation.
The Indus River also provided water and food resources.
