The company was established in 1967 to assemble Leyland vehicles and later Isuzu, Toyota, Nissan, and Chevrolet models as well.

In addition to assembly, the company manufactures its own vehicle brand under the name Thai Rung.

The company was established by Vichien Phaoenchoke in 1967 as Thai Motor Corporation (THAMCO) and began assembling Leyland vehicles.

After Leyland's decline, THAMCO switched its business to assembling Isuzu, Toyota, Nissan, and Chevrolet vehicles in the 1980s and 1990s.

The company was first listed on the Stock Exchange of Thailand on 21 November 1994 (1994-11-21), after it changed its name from THAMCO.