The Ahom language is a nearly extinct Tai language spoken by the Ahom people who ruled the Brahmaputra river valley in the present day Indian state of Assam between the 13th and the 18th centuries. The language is classified in a Northwestern subgrouping of Southwestern Tai owing to close affinities with Shan, Khamti and, more distantly, Thai. As the Ahom rulers of the area assimilated to the more numerous Assamese, the Indo-Aryan Assamese language gradually replaced Ahom as a spoken language, a process which became complete during the 19th century. As of 2000, Ahom was only known by approximately 200 priests of the traditional Ahom religion and only used for ceremonial or ritualistic purposes.