Tools. The Ahom kingdom (/ˈɑːhɔːm/, 1228–1826) was a late medieval kingdom in the Brahmaputra Valley in Assam. It maintained its sovereignty for nearly 600 years having successfully resisted Mughal expansion in Northeast India. Established by Sukaphaa, a Tai prince from Mong Mao (present-day Yunnan Province, China), it began as a mong in.