Evidence for the existence of modern humans and their settlements goes back at least 25,000 years in the form of tools, early art etc. However, "civilization" in the sense of larger, complex and settled communities only emerged much later. Probably the earliest of these communities developed in the "Fertile Crescent" in the Near East, where the Nile, Tigris and Euphrates rivers, as well as the warm climate, allowed agriculture to flourish about 10,000 years ago.
Early cities, like Jericho on the River Jordan, and Catal Huyuk in what is now Eastern Turkey, grew up around this time; by 6250 BCE, Catal Huyuk had a population of at least 6000 and a highly developed culture. Meanwhile, communities were developing along the River Nile; over time, these joined together, becoming "upper and lower Egypt" by 3500 BCE, and forming a united Egypt in 2920. At about this time, the Sumerian city-states of Mesopotamia (now Iraq), also flourished. the Indus Valley, in what is now Pakistan, contained another ancient civilization which ended about 3500 years ago, possibly because of flooding.
Early cities, like Jericho on the River Jordan, and Catal Huyuk in what is now Eastern Turkey, grew up around this time; by 6250 BCE, Catal Huyuk had a population of at least 6000 and a highly developed culture. Meanwhile, communities were developing along the River Nile; over time, these joined together, becoming "upper and lower Egypt" by 3500 BCE, and forming a united Egypt in 2920. At about this time, the Sumerian city-states of Mesopotamia (now Iraq), also flourished. the Indus Valley, in what is now Pakistan, contained another ancient civilization which ended about 3500 years ago, possibly because of flooding.