sentences:  They gained control of Babylonia after the Hittite sack of the city in 1595 BC (i.e.1531 BC per the short chronology), and established a dynasty based first in Babylon and later in Dur-Kurigalzu.The Kassites were members of a small military aristocracy but were efficient rulers and not locally unpopular, and their 500-year reign laid an essential groundwork for the development of subsequent Babylonian culture.