The Kamata Kingdom (pron: ˈkʌmətɑ) emerged in western Kamarupa probably when Sandhya, a ruler of Kamarupanagara, moved his capital west to Kamatapur sometime after 1257 CE. Since it originated in the old seat of the Kamarupa kingdom, and since it covered most of the western parts of it, the kingdom is also sometimes called as Kamarupa-Kamata.
It covered a region corresponding to present-day undivided districts of Kamrup, Goalpara, Jalpaiguri, and Cooch Behar district in India and Rangpur and northern parts of Mymensingh in Bangladesh. The rise of the Kamata kingdom marked the end of the ancient period in the history of Assam and the beginning of the medieval period. The last rulers were the Khens, who were later displaced in 1498 by Alauddin Hussain Shah, the ruler of the Bengal Sultanate. Though Hussain Shah developed extensive administrative structures, he lost political control to a confederation of Baro-Bhuyan within a few years.
Biswa Singha removed the Baro-Bhuyan confederacy and established the Koch dynasty soon, in 1515. The Koches were the last to call themselves Kamateshwars (the rulers of Kamata), but their influence and expansions were so extensive and far-reaching that their kingdom is sometimes called the Koch Kingdom. In the same century the kingdom split in two: Koch Bihar and Koch Hajo. The eastern kingdom, Koch Hajo, was soon absorbed into the Ahom kingdom in the 17th century. The western portion of the Kamata kingdom, Koch Bihar continued to be ruled by a branch of the Koch dynasty and later merged with the Indian territory after the independence of India from the British domain. The boundary between Koch Bihar and Koch Hajo is approximately the boundary between West Bengal and Assam today.
Sandhya, was a ruler of Kamarupanagara, the capital of the erstwhile Kamarupa. After withstanding an attack from Malik Ikhtiyaruddin Iuzbak, in which Iuzbak was killed (in 1257), Sandhya moved his capital to Kamatapur, near present-day Cooch Behar town. Sandhya styled himself Kamateswara and the kingdom came to be known as Kamata.