According to the Northern Thai Chronicles, Lavo was founded by Phraya Kalavarnadishraj, who came from Takkasila in 648 CE.^[16] According to Thai records, Phraya Kakabatr from Takkasila (it is assumed that the city was Tak or Nakhon Chai Si)^[17] set the new era, Chula Sakarat in 638 CE, which was the era used by the Siamese and the Burmese until the 19th century. His son, Phraya Kalavarnadishraj founded the city a decade later.

King Kalavarnadishraj used the name "Lavo" as the name of the kingdom, which came from the Hindu name "Lavapura", meaning "city of Lava", in reference to the ancient South Asian city of Lavapuri (present-day Lahore).^[18] Around the late 7th century, Lavo expanded to the north. Few records are found concerning the nature of the Lavo kingdom. Most of what we know about Lavo is from archaeological evidence.

Around the tenth century, the city-states of Dvaravati merged into two mandalas, the Lavo (modern Lopburi) and the Suvarnabhumi (modern Suphan Buri). According to a legend in the Northern Chronicles, in 903, a king of Tambralinga invaded and took Lavo and installed a Malay prince on the Lavo throne. The Malay prince was married to a Khmer princess who had fled an Angkorian dynastic bloodbath. The son of the couple contested the Khmer throne and became Suryavarman I, thus bringing Lavo under Khmer domination through the marital union. Suryavarman I also expanded into the Khorat Plateau (later styled "Isan"), constructing many temples.

Suryavarman, however, had no male heirs and again Lavo was independent. After the death of King Narai of Lavo, however, Lavo was plunged into bloody civil war and the Khmer under Suryavarman II took advantage by invading Lavo and installing his son as the King of Lavo. The repeated but discontinued Khmer domination eventually Khmerized Lavo. Lavo was transformed from a Theravadin Mon Dvaravati city into a Hindu Khmer one. Lavo became the entrepôt of Khmer culture and power of the Chao Phraya river basin. The bas-relief at Angkor Wat shows a Lavo army as one of the subordinates to Angkor. One interesting note is that a Tai army was shown as a part of Lavo army, a century before the establishment of the "Sukhothai Kingdom".