Kalasin is one of the northeast (Isan) provinces (changwat) of Thailand. The province was established by the Act Establishing Changwat Kalasin, BE 2490 (1947), and it came into existence on 1 October 1947. Neighboring provinces are (from north clockwise) Sakon Nakhon, Mukdahan, Roi Et, Maha Sarakham, Khon Kaen, and Udon Thani. Kalasin is famous for the dinosaur fossils found at Phu Kum Khao (Sahatsakhan District), the largest dinosaur site in Thailand. Most of the fossils are sauropods from 120 million years ago.