Rooted in religion and based on a division of labor, the caste system, among other things, dictates the type of occupations a person can pursue and the social interactions that she may have. Castes are an aspect of Hindu religion. Other religions in India do not follow this system.
-istan is a suffix in the Persian language (Farsi), denoting a place. Thus, Pakistan means place of the pure (pak=pure). It does not just refer to geographical areas, as in bimarestan=place of the sick=hospital. The suffix is widespread in Eurasia because of Persian influence (the Mughals of India for example used Farsi).
The climate of Pakistan. Pakistan is a country located in South-Asia and has one of the largest populations in the world. Most people live in urban areas. Karachi is the largest city with a population of more than 12 million. The landscape of Pakistan varies from low areas in the eastern and southern parts of the country to high plains and high mountain areas in the western and northern parts of the country.