The earliest conflict between Tai people and the preexisting ethnics was recorded in the mid-4th century when the ruler of Singhanavati, , forcibly lost the seat at Yonok to King Khom from Umongasela (present-day Fang). He then fled to Vieng Si Tuang (; present-day Wiang Phang Kham, Mae Sai district) but had to send tributes to Yonok annually until his son, Phrom, took back Yonok and expelled King Khom from Umongasela. Phrom also marched the troops south to occupy Chakangrao from the enemy as well as founding the city of Songkwae. Some historians suggest that Lavo's capital, Lopburi, was once seized by Phrom. In contrast, Tai people instead established relationships with Siamese Mon via royal intermarriages.
The earliest conflict between Tai people and the preexisting ethnics was recorded in the mid-4th century when the ruler of Singhanavati, , forcibly lost the seat at Yonok to King Khom from Umongasela (present-day Fang). He then fled to Vieng Si Tuang (; present-day Wiang Phang Kham, Mae Sai district) but had to send tributes to Yonok annually until his son, Phrom, took back Yonok and expelled King Khom from Umongasela. Phrom also marched the troops south to occupy Chakangrao from the enemy as well as founding the city of Songkwae. Some historians suggest that Lavo's capital, Lopburi, was once seized by Phrom. In contrast, Tai people instead established relationships with Siamese Mon via royal intermarriages