As in Mesopotamia and Egypt, the Indus Valley, with its river Indus and its annual floods, was the main reason for the emergence of the Indian Valley Culture, and its great agriculture, which in turn led to a great civilization was formed that was bigger than all the ancient civilizations. Year after year, when the Indus overflowed, the farmers had abundant harvests, planted wheat and barley, as well as legumes, dates and melons. The societies of farmers, with the passage of hundreds of years, became walled cities, and the cultures of the valley of the Indian, reached more than one million square kilometers. Harappa and Mohenjo-Daro, (in present-day Pakistan) were the most important cities, having their great agricultural potential, thanks to the river Indus, as the main engine of their economy.