The Kassites were an ancient Near Eastern tribe who gained control of Babylonia after the fall of the Old Babylonian Empire after ca. 1531 BC to ca. 1155 BC (short chronology). Their language is classified as an isolate.
The transformation of southern Mesopotamia into a territorial state, rather than a network of allied or combatative temple-cities, made Babylonia an international power. Kassite kings established trade and diplomacy with Assyria, Egypt, Elam, and the Hittites, and the Kassite royal house intermarried with their royal families. There were foreign merchants in Babylon and other cities, and Babylonian merchants were active from Egypt (a major source of Nubian gold) to Assyria and Anatolia. Kassite weights and seals, the packet-identifying and measuring tools of commerce, have been found in as far afield as Thebes in Greece, in southern Armenia, and even in a shipwreck off the southern coast of Turkey.
The Kassite kings maintained control of their realm through a network of provinces administered by governors. Almost equal with the royal cities of Babylon and Dur-Kurigalzu, the revived city of Nippur was the most important provincial center. Nippur, the formerly great city, which had been virtually abandoned ca. 1730 BC, was rebuilt in the Kassite period, with temples meticulously re-built on their old foundations. In fact, under the Kassite government, the governor of Nippur, who took the Sumerian-derived title of Guennakku, ruled as a sort of secondary and lesser king. The prestige of Nippur was enough for a series of 13th century BC Kassite kings to reassume the title 'governor of Nippur' for themselves.
Other important centers during the Kassite period were Larsa, Sippar and Susa. After the Kassite dynasty was overthrown in 1155 BC, the system of provincial administration continued and the country remained united under the succeeding rule, the Second Dynasty of Isin.
Documentation of the Kassite period depends heavily on the scattered and disarticulated tablets from Nippur, where thousands of tablets and fragments have been excavated. They include administrative and legal texts, letters, seal inscriptions, kudurrus (comparable to land grants and administrative prerogatives), private votive inscriptions, and even a literary text (usually identified as a fragment of a historical epic).
"Kassite rulers in Babylon were also scrupulous to follow existing forms of expression, and the public and private patterns of behavior "and even went beyond that — as zealous neophytes do, or outsiders, who take up a superior civilization — by favoring an extremely conservative attitude, at least in palace circles." (Oppenheim 1964, p. 62). Over the centuries, however, the Kassites were absorbed into the Babylonian population. Eight among the last kings of the Kassite dynasty have Akkadian names, Kudur-Enlil's name is part Elamite and part Sumerian and Kassite princesses married into the royal family of Assyria.
The Elamites conquered Babylonia in the 12th century BC, thus ending four hundred years of Kassite rule. The last Kassite king, Enlil-nadin-ahi, was taken to Susa and imprisoned there, where he also died.
The Kassite tribe of Khabira seems to have settled in the Babylonian plain. Remnants of Kassite tribes were living in the mountains northwest of Elam, immediately south of Holwan, when Sennacherib attacked them in 702 BC. They are doubtless the "Kossaeans" of Ptolemy, who divides Susiana between them and the "Elymaeans". Alexander the Great battled Kossaeans in the winter of 323 BC on his way from Ecbatana to Babylon; according to Strabo (xi. 13,3,6) the Kossaeans were the neighbours of the Medes. Theodor Nöldeke (Gott. G. G., 1874, pp. 173 seq.) has shown that they are the Kissians of the older Greek authors who are identified with the Susians by Aeschylus (Choephorae 424, Persians 17, 120) and by Herodotus (v. 49, 52).
There is not a single connected text in the Kassite language. The number of Kassite appellatives is restricted (slightly more than 60 vocables, mostly referring to colors, parts of the chariot, irrigation terms, plants, and titles). About 200 additional lexical elements can be gained by the analysis of the more numerous anthroponyms, toponyms, theonyms, and horse names used by the Kassites (see Balkan, 1954, passim; Jaritz, 1957 is to be used with caution). As is clear from this material, the Kassites spoke a language without a genetic relationship to any other known tongue