From the 21st century BC and likely triggered by the 22nd century BC drought, a large-scale migration of Amorite tribes infiltrated Mesopotamia, precipitating the downfall of the Neo-Sumerian Third Dynasty of Ur, and acquiring a series of powerful kingdoms, culminating in the triumph under Hammurabi of one of them, that of Babylon.
Known Amorites (mostly those of Mari) wrote in a dialect of Akkadian found on tablets dating from 1800–1750 BC showing many northwest Semitic forms and constructions. The Amorite language was presumably a northwest Semitic dialect. The main sources for our extremely limited knowledge about the language are proper names, not Akkadian in style, that are preserved in such texts. Many of these names are similar to later Biblical Hebrew names.
By the time of the Neo-Sumerian Ur-III empire, immigrating Amorites had become such a force that kings such as Shu-Sin were obliged to construct a 170 mile wall from the Tigris to the Euphrates to hold them off . These Amorites appear as nomadic clans ruled by fierce tribal chiefs, who forced themselves into lands they needed to graze their herds. Some of the Akkadian literature of this era speaks disparagingly of the Amorites, and implies that the neo-Sumerians viewed their nomadic way of life with disgust and contempt, for example:
As the centralized structure of the neo-Sumerian empire of Ur slowly collapsed, the component regions began to reassert their former independence, and places where Amorites resided were no exception. Elsewhere, armies of Elam were attacking and weakening the empire, making it vulnerable. Some Amorites aggressively took advantage of the failing empire to seize power for themselves. There was not an Amorite invasion as such, but Amorites did ascend to power in many locations, especially during the reign of the last king of the Ur-III Dynasty, Ibbi-Sin. Leaders with Amorite names assumed power in various places, including Isin, Larsa, and Babylon. The Elamites finally sacked Ur in ca. 2004 BC. Some time later, the most powerful ruler in Mesopotamia (immediately preceding the rise of Hammurabi of Babylon) was Shamshi-Adad I, another Amorite.
The rise of the Amorite kingdoms in Mesopotamia brought about deep and lasting repercussions in its political, social and economic structure.
The division into kingdoms replaced the Sumerian city-state. Men, land and cattle ceased to belong physically to the gods or to the temples and the king. The new monarchs gave, or let out for an indefinite period, numerous parcels of royal or sacerdotal land, freed the inhabitants of several cities from taxes and forced labour, and seem to have encouraged a new society to emerge, a society of big farmers, free citizens and enterprising merchants which was to last throughout the ages. The priest assumed the service of the gods, and cared for the welfare of his subjects, but the economic life of the country was no longer exclusively (or almost exclusively) in their hands.
In general terms, Mesopotamian civilization survived the arrival of Amorites, as it had survived the Akkadian domination and the restless period that had preceded the rise of the Third Dynasty of Ur. The religious, ethical, and artistic directions in which Mesopotamia had been developing since earliest times, were not greatly impacted by the Amorites' hegemony. They continued to worship the Sumerian gods, and the older Sumerian myths and epic tales were piously copied, translated or adapted, generally with only minor alterations. As for the scarce artistic production of the period, there is little to distinguish it from the preceding Ur-III era.
The era of the Amorite kingdoms, ca. 2000-1600 BC, is sometimes known as the "Amorite period" in Mesopotamian history. The principal Amorite dynasties arose in Mari, Yamkhad, Qatna, Assur (under Shamshi-Adad I), Isin, Larsa, and Babylon. This era ended with the Hittite sack of Babylon (c. 1595 BC) which brought new ethnic groups - particularly Kassites and Hurrians - to the forefront in Mesopotamia. From the 15th century BC onward, the term Amurru is usually applied to the region extending north of Canaan as far as Kadesh on the Orontes.
They are described as a powerful people of great stature "like the height of the cedars," who had occupied the land east and west of the Jordan; their king, Og, being described as the last "of the remnant of the giants" (Deut. 3:11).
The terms Amorite and Canaanite seem to be used more or less interchangeably, Canaan being more general, and Amorite a specific component among the Canaanites who inhabited the land.
The Biblical Amorites seem to have originally occupied the region stretching from the heights west of the Dead Sea (Gen. 14:7) to Hebron (13:8; Deut. 3:8; 4:46-48), embracing "all Gilead and all Bashan" (Deut. 3:10), with the Jordan valley on the east of the river (4:49), the land of the "two kings of the Amorites," Sihon and Og (Deut. 31:4; Josh. 2:10; 9:10). Both Sihon and Og were independent kings.
These Amorites seem to have been linked to the Jerusalem region, and the Jebusites may have been a subgroup of them. The southern slopes of the mountains of Judea are called the "mount of the Amorites" (Deut. 1:7, 19, 20). One possible etymology for "Mount Moriah" is "Mountain of the Amorites," with loss of the initial syllable.
Five kings of the Amorites were first defeated with great slaughter by Joshua (10:10). They were said to have been utterly destroyed at the waters of Merom by Joshua (Josh. 11:8). It is mentioned that in the days of Samuel, there was peace between them and the Israelites (1 Sam. 7:14). The Gibeonites were said to be their descendants, being an offshoot of the Amorites that made a covenant with the Hebrews; when Saul would break that vow and kill some of the Gibeonites, God sent a famine to Israel.