The history of Morigaon is obscure. One famous traditional ruler of the region was Arimatta whose history is shrouded in mystery. After Arimattas's death, Jongalbalahu, his son ruled over the region. Jongalbalahu was ultimately killed by the Kacharis with a bamboo spear near Kajalimukh.
The legend further goes on to say that Jongalbalahu to escape his pursuers, submerged himself in Kollong river and emerge at Raha to quench his thirst and again dived here to emerge at Jagi. From this incident were derived the names of present day Raha and Jagi.
The writing of Bhimsingh throws some light on the history of present Morigaon town and its adjoining areas. This region was ruled independently by six rulers. During this time two princes from Darrang, Supradhvaj and Makardhvaj, fled from their homeland due to internal clash, by crossing the mighty Brahmaputra and they settled at Bahakajari. Later on, Supradhvaj married the daughter of Mangalsingh, the King of Baghara. Supradhvaj was then made the seventh king of the region, having an independent kingdom of his own.
During the days of Lachit Borphukan, another two princes from Darrang, Ram Singh and Bhimsingh crossed the Brahmaputra in search of plain lands. After Bhim Singh settled down, meanwhile, Ram Singh left for his home. Bhim Singh was not liked by the local people, hence, he left Brahmaputra and settled down near Mori Beel. This place came to known as Morigaon.
Marigaon became a fully-fledged district on 29 September 1989, when it was split from Nagaon district
