Long periods of the history of the Middle East in antiquity cannot be dated by an absolute chronology or according to a modern system of reckoning. The 'Sumerian King List' gives a succession of rulers to the end of the dynasty of Isin, about 1790 BC, but it is quite unreliable for dates prior to the dynasty of Akkad, about 2340 BC. A relative chronology is well established for the era from the beginning of the dynasty of Akkad to the end of the 1st Dynasty of Babylon, about 1595 BC. This period, however, is followed by an obscure period of more than 700 years, during which dates are only approximate. Scholars follow at least three chronological systems for the ancient Middle East: high, middle, or low, depending upon whether the date assigned to the first year of the reign of Hammurabi of Babylon is 1848, 1792, or 1728 BC. The dates in this article and in that on Sumer follow the so-called middle chronology and date the first year of Hammurabi's reign to 1792 BC.
The Babylonian civilization, which endured from the 18th until the 6th century BC, was, like the Sumerian that preceded it, urban in character, although based on agriculture rather than industry. The country consisted of a dozen or so cities, surrounded by villages and hamlets. At the head of the political structure was the king, a more or less absolute monarch who exercised legislative and judicial as well as executive powers. Under him was a group of appointed governors and administrators. Mayors and councils of city elders were in charge of local administration.
The Babylonians modified and transformed their Sumerian heritage in accordance with their own culture and ethos. The resulting way of life proved to be so effective that it underwent relatively little change for some 1200 years. It exerted influence on all the neighboring countries, especially the kingdom of Assyria, which adopted Babylonian culture almost in its entirety. Fortunately, many written documents from this period have been excavated and made available to scholars. One of the most important is the remarkable collection of laws often designated as the 'Code of Hammurabi', which, together with other documents and letters belonging to different periods, provides a comprehensive picture of Babylonian social structure and economic organization.
During the reigns of Hammurabi and his son Samsu-iluna (r. about 1750-1712 BC), who succeeded him, Babylonian civilization reached the zenith of its cultural development and political power. Some of the more important cities of Babylonia began to seek independence, however, and in the reign of Samsu-iluna, the Kassites first invaded the country. Although Samsu-iluna succeeded in beating them off, the Kassites continued to infiltrate Babylonia in the centuries that followed. Samsu-iluna suffered another serious setback when a rebel leader, Iluma-ilum, founded a dynasty in the southern Babylonian district, bordering on the Persian Gulf, commonly known as the Sea-land.
Under Samsu-iluna's successors Babylonia suffered a serious decline in power and territory. When, about 1595 BC, a Hittite army penetrated as far south as Babylon and carried off Babylonian prisoners and wealth to far-off Anatolia, the kingdom became badly disorganized. Babylonia later fell under the rule of the dynasty of the Sealand, at least for a brief period. Finally, toward the middle of the 16th century BC, a Kassite ruler named Agum (r. about 1570 BC) became master of Babylonia and extended its territory from the Euphrates River to the Zagros Mountains.
Under Kassite rule, Babylonia once again became a power of considerable importance. At the beginning of the 15th century BC, for example, it was one of the four major powers of the Orient, the other three being the Egyptian, Mitanni, and Hittite empires.
After Assyria freed itself of Mitanni domination early in the 14th century BC, its rulers began to interfere in the affairs of Babylonia and sought to control it politically. They were eventually successful, and a weakened Babylonia fell prey to the Elamites, who invaded it from the east, deposed its Kassite king, and practically reduced it to a state of vassalage.
A revolt then broke out in southern and central Babylonia, and a new dynasty, known usually as the 2d Dynasty of Isin, was founded. Toward the end of the 12th century BC, Nebuchadnezzar I (r. about 1125-1103 BC), one of the Isin kings, defeated the Elamites and even attacked Assyria. Soon after, Aramaean nomads began swarming into Babylonia. For about two centuries thereafter the country was in a state of political chaos.

Babylonian society consisted of three classes represented by the awilu, a free person of the upper class; the wardu, or slave; and the mushkenu, a free person of low estate, who ranked legally between the awilu and the wardu. Most slaves were prisoners of war, but some were recruited from the Babylonian citizenry as well. For example, free persons might be reduced to slavery as punishment for certain offenses; parents could sell their children as slaves in time of need; or a man might even turn over his entire family to creditors in payment of a debt, but for no longer than three years.