Koch Hajo (1581-1616) was the kingdom under Raghudev and his son Parikshit Narayan of the Koch dynasty that stretched from Sankosh river in the west to the Bhareli river in the east on the north bank of the Brahmaputra river. It was created by dividing the Kamata kingdom then under Nara Narayan in medieval Assam. The Sankosh river divided the two new kingdoms, and it is roughly the boundary between the present-day Assam and West Bengal. The western half of the Kamata kingdom emerged as Koch Bihar whereas the eastern half emerged as Koch Hajo. The name Hajo comes from the legendary king Hajo, a Koch tribal chief and an ancestor of the Koch dynasty, who ruled over the Rangpur division in present-day Bangladesh and some regions of present-day Assam. Division of Kamata kingdom After the Koch–Ahom conflicts that saw Chilarai briefly occupy Garhgaon, the capital of the Ahom kingdom, Koch rule was consolidated between the Sankosh river in the west and the Subansiri river on the east under the governorship of Chilarai. Chilarai's son, Raghudev, was the heir apparent to the childless Nara Narayan. A son (Lakshmi Narayan) born late to Nara Narayan dashed Raghudev's hopes of becoming the king. Raghudev, accompanied by some trusted state officers, traveled east on a purported hunting trip and declared himself king of the eastern portion at a place called Barnagar near the Manas river. Nara Narayana did not react aggressively, and the kingdom was divided amicably with Raghudev promising to pay an annual tribute. This division occurred in 1581. When Nara Narayan died in 1587, Raghudev stopped paying tribute and declared himself independent. The kingdom under Raghudev included the region between Sankosh and Bhareli rivers on the northern bank of the Brahmaputra river, and on the south the region west of the Kallang river that followed the course of the Brahmaputra as it bends south and right up to the forests of Mymensingh region, now in Bangladesh. Raghudev Narayan Raghudev's declaration of independence established a Koch Bihar-Koch Hajo conflict that was to result in Koch Bihar losing its independence to the Mughal Empire and Koch Hajo losing its very existence both within three decades. Lakshmi Narayan tried to instigate Parikshit, a son of Raghudev, against his father. The plot was detected and Parikshit managed to escape to Koch Bihar. This led to an armed conflict between the two kingdoms, but which maintained