Earlier known as Khagorijan, ancient Nagaon had its headquarters at Puranigudam. It was ruled by the Ahoms who were attacked by the Kacharis, who vandalized a large part of the kingdom. After the Ahoms finally defeated the Kacharis, Ahom officer Momai Tamuli Borboruah was ordered to rebuild the area. Over time, new villages were built. That is how Nagaon (Na meaning new and Gaon meaning village) eventually came about.