A people of the central Zagros mountains who occupied Babylon after the Hittite raid c 1595 BC and who had a distinctive culture and language. Their occupation ended with the city's conquest by Assyria and Elam c 1157 BC. The Kassites may or may not have been Indo-Europeans, but their rulers were probably Indo-Aryan aristocracy who taught them horsebreeding and riding, which they introduced into Mesopotamia. One important source of information on the Kassites was the Amarna correspondence on foreign relations of 14th century BC. The Kassites used distinctive boundary stones called kudurru. The Kassite rule represents the longest episode of political integration in the history of southern Mesopotamia. Important sites are Aqar Quf, Warka, and Nippur.