Arabia, Sahara and Southeast China and India all are on the tropic of Cancer yet Southeast China and India are not deserts. I know that India is not a desert because of monsoon wind which causes heavy rain. But China doesn't have that kind of wind. Also Tibet which is in Southwest China is very dry because the moist air doesn't get over the Himalayas. But east of that you would normally expect there to be another big desert, but there isn't. Why is this?