The geographical site of the origin of rice domestication is not yet definitely known. The general consensus is that rice domestication occurred independently in China, India and Indonesia, thereby giving rise to three races of rice: sinica (also known as japonica), indica and javanica (also known as bulu in Indonesia). There are indications that rice was cultivated in India between 1500 and 2000 B.C. and in Indonesia around 1648 B.C. Archaeological findings have shown that tropical or indica rice was being cultivated in Ho-mu-tu, Chekiang Province, China at least 7 000 years ago (Chang, 1983). Recently, remains of the temperate or sinica (japonica) rice of the same age were found at Lou-jia-jiao, also in Chekiang Province (Chang, 1985). Rice was rapidly dispersed from its tropical (southern and southeastern Asia) and subtropical (southwestern and southern China) habitats to much higher altitudes and latitudes in Asia, reaching Japan as recently as 2 300 years ago (Chang, 1983). It was introduced to points as far as West Africa, North America and Australia within the last six centuries.