Population and Urbanization

South and East Asia contain almost half the world's population. India and China account over a third of the world's population by themselves. As in the other regions we've studied, urban areas in these realms are growing rapidly, yet India and China still contain significant rural populations. What are the factors that contribute to India and China still having such large rural populations? Why might people from these rural areas seek to move to urban areas? Are there any benefits to these populations remaining rural?