The foreign invaders appeared in India in the 8th century. Slaughter, raping, looting, kidnapping, etc were the widespread practice of Muslims although their rule. They devastated and brutalized India for 1200 long year. Take for granted they killed and pogrom half a million Hindus inhabitants each year or 500,000 inhabitants a year. Then multiply that figure by 1200. It becomes 600 millions. Muslims slaughter 500,000 Hindu inhabitants a year is quite a practical approximation [the real number can be even upper].