Tropical Asia is a region comprising South and Southeast Asia and under strong influence of the Asian monsoon climate. It is characterized by an extremely high population density and by high land use intensity. Paddy rice cultivation is the most important form of agriculture in the greater part of the region. Soil resources of tropical Asia have a specific feature in comparison with tropical Africa and America. Ultisols dominate in uplands, and lowland soils like Inceptisols and Histosols are relatively abundant. The latter point is made clearer if we take the landforms of the region with a vast extent of lowlands into consideration. Geologically, tropical Asia with the Himalayan orogeny and active volcanism exhibits a conspicuous contrast to tropical Africa and America with the dominance of the shield structure. This along with the monsoon climate should have determined the basic features of landforms and soil, and accordingly all the agricultural and social characteristics of tropical Asia today. Alth It is characterized by an extremely high population density and by high land use intensity. Paddy rice cultivation is the most important form of agriculture in the greater part of the region. Soil resources of tropical Asia have a specific feature in comparison with tropical Africa and America. Ultisols dominate in uplands, and lowland soils like Inceptisols and Histosols are relatively abundant. The latter point is made clearer if we take the landforms of the region with a vast extent of lowlands into consideration. Geologically, tropical Asia with the Himalayan orogeny and active volcanism exhibits a conspicuous contrast to tropical Africa and America with the dominance of the shield structure. This along with the monsoon climate should have determined the basic features of landforms and soil, and accordingly all the agricultural and social characteristics of tropica l Asia today. Alth