What is the process to hire Indians, Pakistanis, Nepalis and Philipines for company of Saudi Arabia?

I would suggest that it is because workers of the countries you have nominated are lower "maintenance" than their western counterparts, in so much as their needs, salaries and expectations are lower and they therefore represent better value for money.This is in no way meant disrespectfully but instead boils down to the particular "standards of living" that people have become accustomed to, it has nothing to do with ability, culture, religion, colour or anything else.