The weakening of the Semitic states in Mesopotamia after 1550 enabled the Hurrians to penetrate deeper into this region, where they founded numerous small states in the eastern parts of Anatolia, Mesopotamia, and Syria. The Hurrians came from northwestern Iran, but until recently very little was known about their early history. After 1500, isolated dynasties appeared with Indo-Aryan names, but the significance of this is disputed. The presence of Old Indian technical terms in later records about horse breeding and the use of the names of Indian gods (such as, for example, Indra and Varuna) in some compacts of state formerly led several scholars to assume that numerous groups of Aryans, closely related to the Indians, pushed into Anatolia from the northeast. They were also credited with the introduction of the light war chariot with spoked wheels. This conclusion, however, is by no means established fact. So far it has not been possible to appraise the numbers and the political and cultural influence of the Aryans in Anatolia and Mesopotamia relative to those of the Hurrians.

Some time after 1500 the kingdom of Mitanni (or Mittani) arose near the sources of the Khābūr River in Mesopotamia. Since no record or inscription of their kings has been unearthed, little is known about the development and history of the Mitanni kingdom before King Tushratta. The Mitanni empire was known to the Egyptians under the name of Naharina, and Thutmose III fought frequently against it after 1460 bce. By 1420 the domain of the Mitanni king Saustatar (Saushatar) stretched from the Mediterranean all the way to the northern Zagros Mountains, in western Iran, including Alalakh, in northern Syria, as well as Nuzi, Kurrukhanni, and Arrapkha. The northern boundary dividing Mitanni from the Hittites and the other Hurrian states was never fixed, even under Saustatar’s successors Artatama I and Shuttarna II, who married their daughters to the pharaohs Thutmose IV (1400–1390) and Amenhotep III (1390–1353). Tushratta (c. 1365–c. 1330), the son of Shuttarna, was able to maintain the kingdom he had inherited for many years. In his sometimes very long letters—one of them written in Hurrian—to Amenhotep III and Akhenaton (1353–1336), he wrote about commerce, his desire for gold, and marriage. Weakened by internal strife, the Mitanni kingdom eventually became a pawn between the rising kingdoms of the Hittites and the Assyrians.

The kingdom of Mitanni was a feudal state led by a warrior nobility of Aryan or Hurrian origin. Frequently horses were bred on their large landed estates. Documents and contract agreements in Syria often mention a chariot-warrior caste that also constituted the social upper class in the cities. The aristocratic families usually received their landed property as an inalienable fief. Consequently, no documents on the selling of landed property are to be found in the great archives of Akkadian documents and letters discovered in Nuzi, near Kirkūk. The prohibition against selling landed property was often dodged, however, with a stratagem: the previous owner “adopted” a willing buyer against an appropriate sum of money. The wealthy lord Tehiptilla was “adopted” almost 200 times, acquiring tremendous holdings of landed property in this way without interference by the local governmental authorities. He had gained his wealth through trade and commerce and through a productive two-field system of agriculture (in which each field was cultivated only once in two years). For a long time, Prince Shilwa-Teshub was in charge of the royal governmental administration in the district capital. Sheep breeding was the basis for a woolen industry, and textiles collected by the palace were exported on a large scale. Society was highly structured in classes, ranks, and professions. The judiciary, patterned after the Babylonian model, was well organized; the documents place heavy emphasis on correct procedure.

Native sources on the religion of the Hurrians of the Mitanni kingdom are limited; about their mythology, however, much is known from related Hittite and Ugaritic myths. Like the other peoples of the ancient Middle East, the Hurrians worshiped gods of various origins. The king of the gods was the weather god Teshub. According to the myths, he violently deposed his father Kumarbi; in this respect he resembled the Greek god Zeus, who deposed his father Kronos. The war chariot of Teshub was drawn by the bull gods Seris (“Day”) and Hurris (“Night”). Major sanctuaries of Teshub were located at Arrapkha (modern Kirkūk) and at Halab (modern Aleppo) in Syria. In the east his consort was the goddess of love and war Shaushka, and in the west the goddess Hebat (Hepat); both were similar to the Ishtar-Astarte of the Semites.

The sun god Shimegi and the moon god Kushuh, whose consort was Nikkal, the Ningal of the Sumerians, were of lesser rank. More important was the position of the Babylonian god of war and the underworld, Nergal. In northern Syria the god of war Astapi and the goddess of oaths Ishara are attested as early as the 3rd millennium bce.

In addition, a considerable importance was attributed to impersonal numina such as heaven and earth as well as to deities of mountains and rivers. In the myths the terrible aspect of the gods often prevails over indications of a benevolent attitude. The cults of sacrifices and other rites are similar to those known from the neighbouring countries; many Hurrian rituals were found in Hittite Anatolia. There is abundant evidence for magic and oracles.

Temple monuments of modest dimensions have been unearthed; in all probability, specific local traditions were a factor in their design. The dead were probably buried outside the settlement. Small artifacts, particularly seals, show a peculiar continuation of Babylonian and Assyrian traditions in their preference for the naturalistic representation of figures. There were painted ceramics with finely drawn decorations (white on a dark background). The strong position of the royal house was evident in the large palaces, existing even in district capitals. The palaces were decorated with frescoes. Because only a few Mitanni settlements have been unearthed in Mesopotamia, knowledge of Mitanni arts and culture is as yet insufficient.