You will find that the first civilizations were built around rivers. Do you know why? One reason was that rivers ensured a supply of water for farming, building, and washing, drinking, and cooking. The flood-waters of rivers made the land very fertile, and the rivers made transportation easy. Consequently, rivers helped in the development of trade and commerce. Rivers also inspired new technological and economic innovations and developments, like dams, dykes, sluices and canals. As a result, between 3000 and 2000 BC, river valley civilizations formed independently of each other along the Indus, the Nile, the Tigris and Euphrates, and the Yellow Rivers.