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).
Languages: Pakistan is composed of two main groups of languages: Indo-Iranian and Indo-Aryan. Indo-Aryan group of languages: Urdu. Punjabi. Sindhi. Sairaki. Dardic languages like Shina and Kashmiri. Indo-Iranian languages: Pashto. Balochi. Then there is one Dravidian language: Brahui. These above are the main languages of Pakistan