Lamphun was the capital of the small but culturally rich Mon Kingdom of Haripunchai from about 750 CE to the time of its conquest by King Mangrai (the founder of Chiang Mai) in 1281.

Lamphun became famous after the enthronement of Queen Chama Thewi (Chamadevi), probably during the late 9th or early 10th century CE. The Lan Na chronicles, verified where possible by archaeology and other corroborative texts, suggest that the foundations of the Kingdom of Haripunchai were laid at Lamphun by a group of Buddhist monks from Lopburi some time in the 8th or 9th century CE.

These monks asked the Mon king of Lopburi to provide them with a ruler for their city, and he sent his daughter, Chama Thewi, who arrived in Lamphun accompanied by a large retinue of Mon retainers. The new queen was a woman of strong character, who tenaciously defended the interests of Haripunchai against the local Lawa people, and actively promoted Buddhism in the region. She founded a dynasty that was to last until the mid-11th century, and established her capital, Lamphun, as an important centre of Mon culture and influence.