The first great civilizations all developed in river valleys, as the rivers provided a source of water and irrigation for crops. Over time, these civilizations developed a surplus of food that allowed them to create specialization of trades.
The Tigris-Euphrates Rivers gave rise to the first civilization, Mesopotamia, around 3500 BCE. The city-states in Mesopotamia began to irrigate their land using the two rivers. Egypt developed along the Nile, which had a different type of flood cycle than the Tigris and Euphrates. While the Tigris and Euphrates had unpredictable floods that varied in scope, the Nile had predictable flooding patterns. The Tigris and Euphrates had floods that could be much greater in volume one year than in other years, so the people in Mesopotamia had to control the flooding with dikes. The people along the Nile used the river's predictable flooding patterns to irrigate their crops, and they also developed dikes, canals, and basins.
The Indus River is longer than the other rivers, and its annual length of flow is two times that of Nile and three times as long as the Tigris and Euphrates. In its upper plain, the Indus has several tributaries, but in its lower plain, it is like the Nile in having few tributaries. The Indus, like the Nile, also floods in a way that creates rich alluvial soil.