Rice hull imprints on bricks of the Dvaravati Period from four historical sites in Thailand and Lao PDR were measured and classified. In addition, a collection of traditional rice landraces from northern, central, northeastern regions of Thailand, Lao PDR, Vietnam and Cambodia were used to examine rice grain shapes and to test phenol reaction response of rice hulls. The results show that rice hulls in bricks from the Dvaravati Period may be classified into three types of cultivated rice grain shapes, i.e., round, large, and slender types. With the combined methods in archaeology, physiology and ecotype, the present domesticated rice landraces have been combined and by implication, can be possibly traced to types of rice in the Dvaravati Period. It is now suggested that the subspecies indica and japonica of Asian cultivated rice were domesticated at that time.