In 1996 Chiangmai, the capital of the Lanna Kingdom, celebrated its 700th year of continuous development. At its greatest extent the Lanna Kingdom included areas of southern China, Burma, Laos and Northern Thailand. Lanna history begins in 1296 with Mangrai's conquest of Hariphunchai and his foundation of Chiangmai as the new capital. At that time the region was populated by several ethic groups, the largest of whom were the Tai Yuan. Early settlements had been established in the valleys of the Mekong, Ping, Yom, Wang, Nan and Ing rivers. Chiangmai absorbed many aspects of Hariphunchai culture including Buddhism and the arts. In time Chiangmai became the pre-eminent city in Lanna for politics, economics, social life and religious philosophy: the greatest influence on its culture was Buddhism. Mangrai's dynasty ruled Lanna as an independent Kingdom for almost 200 years untill in 1558 it came under Burmese rule. Two centuries later in 1774 Lanna cast off the Burmese Yoke but lost its unity: the old kingdom was divided into a number of Thai tributary states. In 1904 under the reign of King Chulalongkorn (Rama 5), the Siam government abolished the tributary system and integrated the right Lanna city states into Siam. Lanna became a "monthon" (circle) under the name Monthon Phayap. In 1933 in the reign of King Prachathipok (Rama 7) the Monthon Phayap was divided into eight changwat or provinces, namely: Chiangmai, Lamphun, Lampang, Phrae, Nan, Chiangrai, Phayao and Maehongson. Law constitutes one of the important aspects of a country’s administration. It is the most important medium to understand the character of a government. The study in the Tai traditional legal system is complicated because a sufficient quantity of recorded materials is lacking. However, contemporary legal anthropology fills the gap as it provides convincing evidence that the Tai - the irrigated rice growers - whenever and wherever they lived, had detailed rules and regulations constituted in the form of “positive law”. This article attempts to present an account of the Ahom jurisprudence, meaning “positive law”, as it existed in the pre-British Assam state of India.