Multiple cropping is widely practised in tropical Asia (the area between the Himalayan mountains and the equator from Pakistan and India to Indonesia, New Guinea, the Philippines, southern Taiwan, the southeastern portion of the People's Republic of China and mainland southeast Asia). The dominant crops in the region are mainly determined by water supply. Cropping systems in the drier regions of India and Pakistan are based on corn, sorghum, millet and wheat, while the wetter areas of these same countries are nearly all of east Asia, having high rainfall, are rice based.