The Ahom Kingdom (1228–1826, called Kingdom of Assam in medieval times) is a medieval kingdom in the Brahmaputra valley in Assam that maintains its sovereignty for nearly 600 years and successfully resists Mughal expansion in North-East India.

It is able to establish its suzerainty over the Brahmaputra valley and has a profound effect on the political and social life in the region.

The kingdom is established by Sukaphaa, a Tai prince from Mong Mao, in the upper reaches of the Brahmaputra river between the extant Chutiya kingdom in the north and the Kachari kingdom in the south.

The kingdom expands north, south and the west in succession and evolves into a multi-ethnic polity, beginning especially under Suhungmung Dihingia Raja in the 16th century.

It makes major advances under Susenghphaa Pratap Singha, under whom the administration is revamped and the first military and diplomatic contact with the Mughals are made.

Mughal influence is completely removed from much of the Brahmaputra valley under Gadadhar Singha and the Ahom kingdom reaches its zenith under his son, Rudra Singha.

The kingdom becomes weaker with the rise of the Moamoria rebellion, and subsequently falls to a succession of Burmese invasions.

With the defeat of the Burmese after the First Anglo-Burmese War and the Treaty of Yandabo in 1826, control of the kingdom passes into British (East India Company) hands.Though it comes to be called the Ahom kingdom in the colonial and subsequent times, it is largely multi-ethnic, with the ethnic Ahom people constituting less than 10% of the population toward the end.

The Ahoms call their kingdom Mong Dun Shun Kham, (Assamese: xunor-xophura; English: casket of gold) while others call it Assam.

The British-controlled province after 1838 and later the Indian state of Assam comes to be known by this name.