In what regions did early farmers use irrigation systems?

Early farmers used irrigation systems primarily in regions with arid or semi-arid climates where rainfall was insufficient for agriculture. Notable areas include the Nile River Valley in Egypt, the Tigris and Euphrates river valleys in Mesopotamia, and the Indus River Valley in South Asia. Additionally, early irrigation practices were developed in regions like ancient China and the southwestern United States, enabling the cultivation of crops in otherwise inhospitable environments. These systems allowed for more reliable food production and supported the growth of early civilizations.