Sumer
Sumer () is the earliest known civilization in the historical region of southern Mesopotamia, modern-day southern Iraq, during the Chalcolithic and Early Bronze ages, and one of the first civilizations in the world along with Ancient Egypt and the Indus Valley. Living along the valleys of the Tigris and Euphrates, Sumerian farmers were able to grow an abundance of grain and other crops, the surplus of which enabled them to settle in one place. Prehistoric proto-writing dates back before 3000 BC. The earliest texts, from c. 3300 BC, come from the cities of Uruk and Jemdet Nasr; early cuneiform script emerged around 3000 BC.
Cradle of civilization
Around 10,200 BC the first fully developed Neolithic cultures belonging to the phases Pre-Pottery Neolithic A (PPNA) and Pre-Pottery Neolithic B (7600 to 6000 BC) appeared in the Fertile Crescent and from there spread eastwards and westwards. One of the most notable PPNA settlements is Jericho in the Levant region, thought to be the world's first town (settled around 8500 BC and fortified around 6800 BC). In Mesopotamia, the convergence of the Tigris and Euphrates rivers produced rich fertile soil and a supply of water for irrigation. The civilizations that emerged around these rivers are among the earliest known non-nomadic agrarian societies. It is because of this that the Fertile Crescent region, and Mesopotamia in particular, are often referred to as the cradle of civilization. The period known as the Ubaid period (c. 6500 to 3800 BC) is the earliest known period on the alluvial plain, although it is likely earlier periods exist obscured under the alluvium. It was during the Ubaid period that the movement towards urbanization began. Agriculture and animal husbandry were widely practiced in sedentary communities, particularly in Northern Mesopotamia, and intensive irrigated hydraulic agriculture began to be practiced in the south.