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.
History of the Maya civilization
The history of Maya civilization is divided into three principal periods: the Preclassic, Classic and Postclassic periods; these were preceded by the Archaic Period, which saw the first settled villages and early developments in agriculture. Modern scholars regard these periods as arbitrary divisions of chronology of the Maya civilization, rather than indicative of cultural evolution or decadence. Definitions of the start and end dates of period spans can vary by as much as a century, depending on the author. The Preclassic lasted from approximately 2000 BC to approximately 250 AD; this was followed by the Classic, from 250 AD to roughly 950 AD, then by the Postclassic, from 950 AD to the middle of the 16th century. Each period is further subdivided: