The Sumerians, building on previous societies, founded complex political, economic, social, and cultural superstructures and therefore came to be regarded as one of the world’s earliest civilizations.

“Mesopotamia,” based on the Greek for “land between the rivers,” is used to describe what many historians define as the world’s earliest civilization. This civilization arose between the Tigris and Euphrates Rivers, a mess of mud, clay, and reedy swamps roughly 200 miles (320 kilometers) long and 100 miles (160 kilometers) wide (at its widest point). This area was subject to torrential rainstorms, periodic flooding, sweltering heat, and blazing sunlight. By 6000 b.c.e., the agricultural revolution brought settled Neolithic societies to the hilly north and to the mountains east of Mesopotamia, but not until a thousand years later were agricultural techniques sufficiently understood for a few adventuresome peoples to migrate into these inhospitable river plains. It would take another thousand years for the Sumerians to build on the work of previous cultures and turn a scattering of settlements into a series of thriving city-states.

In central Mesopotamia, the Samarra culture (5500-5000 b.c.e.) established agricultural settlements. Houses, built with mud and clay bricks, appear to have contained about ten rooms. Ceramic wares and grain were traded for copper (used in jewelry) and for semiprecious stones such as obsidian and turquoise. By 5000 b.c.e., a few small settlements extended into southern Mesopotamia. In northern Mesopotamia, Halafian culture (5500-4500 b.c.e.) established settlements, which took the form of a large number of tiny communities, and the Halafians engaged in extensive trade of their distinctive pottery.

The Ubaid people (named after Tell-al Ubaid in southern Mesopotamia near what would become the city of Ur and now is Muqaiyir) are generally credited with the settlement of southern Mesopotamia and the creation of more complex towns. Use of the slow wheel and unlimited access to clay resulted in the production of large amounts of greenish colored pottery decorated with brown or black geometric designs and loop handles. This distinctive pottery appears to have eclipsed that of the Samarrans and Halafians in popularity.

The Ubaid people developed irrigation and marsh-drainage techniques to allow them to practice agriculture along the Tigris and Euphrates Rivers. Without irrigation and canals, the fierce storms that struck during the spring and caused the river to flood would have made planting impossible. The rich mud of the plains produced bountiful crops of barley, lentils, and wheat. Fired clay was used to create hoes, adzes, sickles, and other tools. They raised cattle, largely as work animals; sheep for wool; and goats for their milk, which was turned into cheese. Like the Samarrans, the Ubaid people built houses made of molded sun-dried mud brick. However, unlike the Samarran settlements, Ubaid towns kept on expanding in both size and complexity. By 4500 b.c.e., towns numbering several thousand inhabitants were not uncommon. The largest of these was Eridu (site south of present-day An Nāsirīyah, Iraq), which had houses crowded together, forming narrow alleyways. Houses were built on a tripartite plan: A full-length large rectangular room was flanked with rows of smaller rooms on each side. Larger houses, apparently constructed for the upper class, contained storage facilities. Eridu also contained a large, richly decorated temple built of mud brick and supported by complicated buttresses and niches. This temple was first excavated by Sir Leonard Woolley in 1922. The simplest houses, often composed of reed, were reserved for the farmers who lived on the outskirts of Eridu.

Because mud bricks are weakened by rain, buildings in Eridu and other Ubaidan settlements lasted no longer than a generation. Each rebuilding seems to have resulted in larger buildings, general expansion of the size of the town, and much larger temples (suggesting that irrigation projects were directed by a priestly elite). Trade for precious stones extended to distant India and down into the Persian Gulf and modern-day Saudi Arabia, where a number of Ubaid trading outposts were constructed. To direct northern trade, Ubaidans constructed Tepe Gawra (discovered in 1927 by the archaeologist Ephraim Speiser, near modern Mosul, Iraq), which contained three large temples similar to the one found at Eridu. By 4300 b.c.e., when the Sumerians arrived on the Mesopotamian river plains, they catalyzed a process already in motion of producing sophisticated, ever-expanding towns with linked agricultural and trading communities.

The Sumerians, who called themselves “the black-headed peoples,” spoke a monosyllabic language unrelated to any other language group. Their origins (probably India, Persia, and the area around the Caspian Sea) and relationship to any other known ethnic group have yet to be determined. The Sumerians soon dominated and eclipsed their Semitic-speaking neighbors. They introduced improved and new techniques that led to continued population growth and urbanization, resulting in what can be called the advent of civilization.

Sumerian innovations included the building of roads on which donkeys brought goods to market and canals to more efficiently irrigate fields and to facilitate the transportation of goods by boat. The Sumerians were building the infrastructure necessary for complex urban life. They invented the quick wheel for the mass production of pottery. They built channels, dikes, and reservoirs for flood control and water conservation. Considerable care was devoted to the cultivation of dates, trees that do not self-pollinate and require five years of nurturing before they produce their high-energy and vitamin-laden fruits. Evidence suggests that a priestly class might have had a role in directing economic activity and extracting tribute in return. Record keeping began in the form of clay tokens imprinted with the characteristic seals of the two parties involved in a contract. Other inscriptions probably denoted the item involved and represent pre-cuneiform writing. The shape of the token denoted the quantities involved (small cone = one, circle = ten, large cone = sixty). In this way, the Sumerians were developing mathematical systems in addition to record keeping and writing.

By 4000 b.c.e., Uruk (called Erech in the Bible and identified as Warka in modern Arabic; site northwest of modern-day Muqaiyir, Iraq) began to emerge as the major Sumerian center, a model for what would become, over the course a millennium, twelve major Sumerian city-states. The city-state appears to have resulted from the merging of two neighboring settlements, Kullaba and Eanna. The city was dedicated to the goddess of love, Inanna (later called Ishtar), and a mound temple was built to honor her. Inanna had been the patron goddess of Eanna. Another temple was dedicated to the sky god Anu, the patron god of Kullaba. Both temples were based on the Ubaid style, and both were rebuilt many times, forming two of the several ziggurat temple complexes in Uruk. Security considerations also came to the fore, and work began on a wall that was to surround the city (eventually reaching 6 miles, or 9.5 kilometers, in length) and was to be surrounded by a moat for further protection. The semilegendary first king of Uruk, Gilgamesh, is credited with completing the walled fortifications.

Organized human activity was able to overcome harsh environmental obstacles and exploit the agricultural potential of the fertile Mesopotamian plains, creating a population explosion in a limited geographic area. The resulting food surplus sustained increasing numbers of artisans, craftspeople, and merchants living in continually expanding urban centers. Capitalizing on developments over the previous thousand years, the Sumerians introduced new advancements, resulting in the creation of Uruk, an urban center large enough to be considered the world’s first city-state. Located on the Euphrates River, Uruk was a seminal influence for the development of other Sumerian city-states such as Ur, Kish, and Lagash. Through wide-ranging trade by land and sea, the Sumerian civilization influenced the development of civilization in other Middle Eastern as well as Asian societies. Although the process of civilization was taking place in other river-based agricultural societies, Mesopotamia was transformed earlier and more extensively. Rapid population growth, urbanization, complex social stratification, and extensive trade were first experienced by the Sumerians in Mesopotamia; these steps toward civilization would be followed elsewhere. For this reason, Mesopotamia has long been regarded as the cradle of civilization.

• Kramer, Samuel N. The Sumerians. Chicago: University of Chicago Press, 1990. An overview of the Sumerian culture in Mesopotamia.
• Nemet-Nejat, Karen R. Daily Life in Ancient Mesopotamia. Westport, Conn.: Greenwood Press, 1998. An updated and well-organized account of daily life in ancient Mesopotamia written with the general reader in mind.
• Oppenheim, A. Leo. Ancient Mesopotamia: Portrait of a Dead Civilization. Chicago: University of Chicago Press, 1986. A well-written and illustrated introduction to the growth of Mesopotamia based on interesting historical and archaeological data.
• Pollack, Susan. Ancient Mesopotamia. New York: Cambridge University Press, 1999. A scholarly and well-illustrated anthropological study of life in Mesopotamia.
• Postgate, J. Nicholas. Early Mesopotamia: Society and Economy at the Dawn of History. New York: Routledge, 1994. A readable description of city life, economic activity, and the role of kings, priests, and scribes in Mesopotamia.
• Rothman, Mitchell S., ed. Uruk, Mesopotamia, and Its Neighbors: Cross Cultural Interactions in the Era of State Formation. Santa Fe, N.Mex.: School of American Research Press, 2001. Twelve field and theoretical archaeologists discuss the causes of urban expansion, cross-cultural influences, and life in the fifth and fourth millennia b.c.e.