Mangrai, born in Chiang Saen as son of the local ruler Lao Meng and Princess Ua Ming Chommuong, from the ruling family of the Thai Lue of Chiang Rung, Yunnan, had in 1259 succeeded his father and become the first independent Lao King of unified Lao city states in what is today northern Thailand and northern Laos.

The kingdom, Lanna, or Lannathai, grows quickly by unifying local Tai rulers of the area under his leadership.

Mangrai founds Chiang Rai in 1262 as the first capital of the kingdom; it will ultimately lose this status, however, to a new city built by Mangrai at Chiang Mai.

Subsequently, Chiang Rai will be conquered by the Burmese and remain under their rule for several hundred years.