Legend has it that in 638 AD, or perhaps 650, a deity was born on Doi Tung, and came to be called Luajongarat (Lavacakraraj). This progenitor of Mengrai's line became the first 'Sovereign of Lao'. Relics of the Buddha are said to be enshrined in a pagoda there, on Doi Tung, built soon after 700AD. Local chronicles say that in 731, a king called Khun Borom founded Muong Theng (now Mang Thin, around Dien Bien Phu, where much later the Vietnamese defeated the French colonial army). Khun Borom's sons reportedly founded many important cities, including Xieng Khouang (site of the Plain of Jars) in 698AD, Luang Prabang, Lan Sang (Land of a Million Elephants) in 737), and Chiang Saen in 773. Chiang Saen was first called Nagapan-Singhonawat, then later Yonok Naknakorn or Yonoka. The founder of the kingdom of Nagapan-Singhonawat (though a predecessor of Chiang Saen, situated north across the Mekong River), Prince Singhonawat, is reputed to have reigned 102 years after coming with 100,000 men and women to supplant the Khmers. As a Naga named Bandhu was said to have aided him, the first capital was variously known as Yonokanagara, Yonoka Nagabandhunagara (Yonok Naga Bandhu), and Bandhusinghanati Ngara. Yonok may have existed even earlier as Jayasena or Siam Ban/Vien Siam, which reportedly sent messengers to the Tang Emperor in 625 AD.

It's said that in the 9th Century King Brahmakumara of Jayaprakara (Chai Prakan, now Fang) drove the Khmer from the north. That there were Khmer in the north later is not contested, but it seems doubtful there were ever many in the Lanna area (unless the Lawa are to be considered related). But there were Khom invasions, perhaps as far north as Chiang Tung (Keng Tung). They were well resisted north of Sukhotai, but took the Chiang Saen area for a second time in 1080, ruling until 1099.

Chinese chronicles say that in 1180 AD King Piao Zhen, or Bazhen, founded Jinglong, which may have become Cheli, then Chiang Rung. The records are unclear, except as clearly exaggerated (with a population tally of 8,440,000 and 9000 white elephants); other names associated with this kingdom are Jingxian, Manjianglan, Jinghong, Mengyong Land of Peacocks, and Le Shi. The Emperor of the Heavenly Imperial Court proclaimed Bazhen King of Jiujiang, the domain of which included Lanna, Mengjia and Menglao (Nanzhang or Yingzhan; Laos). What's interesting here is a story parallel to the one of the paragraph above: Bazhan had 4 sons who started 4 new dynasties - they ruled Lanna, Menjia, Meng Lao and Jinglong. Some or all of this was Yonoka, Siam Ban or Vien Siam. One city is referred to as Wen Chan, Muang Chan, Vien Chang, Yun Shan, Nien Chang and Jiangxian. The similarities to Vientianne are clear; that there were any cities of size and significance in Laos before 1180 AD is not. It's likely the towns or principalities of the time weren't large at all.

Much earlier, during the reign of King Mahachai, son of Mahawan, about 800AD, a great earthquake moved water from a great lake at Keng Tung (Tungkalasi, perhaps the Chinese Big Lake Krase) to the area between Doi Tung and Doi Jom Tong. That area, from the Khong to the Kok, remained a lake and extensive marsh for hundreds of years. The city which later became known as Chiang Saen was flooded. An antecedent of Mengrai, Lao Chakra or Lao Khiang, rebuilt Nagapan-Siphonawat near its old site but north of the Mae Khong (Mekong) River, and called it Hiram (or Heranna) Ngoen Yang, around 937AD (various names include Heranya Nakorn, Heranagara, and Hiranya). Ngoen Yang expanded through the 13th century, and became known as Yonok Naknakorn. Ruins at the present Chiang Saen date back only to about the time of Mengrai, but despite major ups and downs, for over 1300 years there has always been a Chiang Saen of one sort or another (surely some previous locations remain under water).

Of the earlier inhabitants of the Lanna region, we've mostly just archaeological evidence and legend. The first Buddhist influence probably antidates the first T'ai, coming to the Lawa many centuries before Mengrai.

In 832 AD the western Chinese kingdom of NanChao destroyed the P'iao Kingdom of Burma, and afterwards the Pagan Kingdom arose. Pagan became strong under King Anoratha (also known as Anawrata and Hinuana, perhaps 1044 - 1077; alternately, he built Pagan in 1010). Anoratha converted from Mahayana to Hinnayana (Theravada) Buddhism and is likely to have demanded tribute from towns in the area which became Lanna. He established close ties with Sri Lanka and may have been responsible for the arrival of the Emerald Buddha. That so precious a thing might have come through Aranachel Pradesh, with its multitudes of headhunters, or by some circuitous route, around Mon, Pyu and other rulers who would surely have been interested to keep such a thing, seems quite unlikely, but is possible. This image, the most sacred in Thailand, may not be so old as is sometimes claimed, and it may well have been in Cambodia during Anoratha's time. That it was in Lanna later is certain; only how it got there is not. The Buddha had given express proscriptions against images of himself; in earlier times replicas of his chair were used as a reminding focus for worshipful meditations.

The Shan states of Mogaung (Momeik), Muong Nai and Hsenwi were powerful by 1228. A T'ai conquest of all Laos and much of the Pagan Empire in Burma (particularly what is now the Mandalay area), as well as an attack on NanChao, is attributed to King Hso Hkan Hpa, but the truth of this is quite doubtful.

T'ais arrived at the Chao Phraya Basin in force in the early to mid 13th century, after the Khom-Angkor Empire lost its power. Sometime between 1220 and 1238 AD, T'ai chieftains attacked and defeated the Khom, or Khmer, at Sukhotai (founded about 70BC). The religious nature of kingship, and the style of rule in the area, got much of its character from the Khom rulers, but influence also came from the longer lasting Mon-Dvaravati Empire. The Khom, however, were the first to cultivate rice in the region, and long held a large empire; they were also ancient history's greatest builders (insofar as we can measure today).