Sumer

Sumer is the earliest known civilization in the historical region of southern Mesopotamia (now southern Iraq), during the Chalcolithic and Early Bronze Ages, and one of the first civilizations in the world, along with Ancient Egypt, Norte Chico, Ancient Greece, Ancient China and the Indus Valley. Living along the valleys of the Tigris and Euphrates, Sumerian farmers grew an abundance of grain and other crops, the surplus from which enabled them to form urban settlements. Prehistoric proto-writing dates back before 3000 BC.

Quotes

• By the end of the fourth millennium B.C. the material culture of Abydos, Ur, or Mohenjo-daro would stand comparison with that of Periclean Athens or of any medieval town. . . . Judging by the domestic architecture, the seal-cutting, and the grace of the pottery, the Indus civilization was ahead of the Babylonian at the beginning of the third millennium (ca. 3000 B.C.). But that was a late phase of the Indian culture; it may have enjoyed no less lead in earlier times. Were then the innovations and discoveries that characterize proto-Sumerian civilization not native developments on Babylonian soil, but the results of Indian inspiration? If so, had the Sumerians themselves come from the Indus, or at least from regions in its immediate sphere of influence?”
  • V. Gordon Childe .Quoted in Durant, Will (1963). Our Oriental heritage. New York: Simon & Schuster.