Today, there are over 500 million Muslims throughout the Indian subcontinent (India, Pakistan, and Bangladesh), making it one of the largest population centers of Muslims in the world. Since Islam first entered India, it has contributed greatly to the area and its people. Today, numerous theories about how India came to be such a largely Muslim land exist. Politically, some (such as the Hindutva movement in India) try to make Islam seem foriegn to India, by insisting it only exists because of invasions by Arab and Persian Muslims. The truth, however, is far from that.
In the early 600s, a new religious and political force arose out of the deserts of Arabia. Islam, spearheaded by Prophet Muhammad ﷺ, quickly became the way of life for the entire Arabian Peninsula within a few years of the first revelations. By the end of the reigns of the first four caliphs, the Islamic realm extended from Libya in the West to Persia in the East. And just 100 years after the death of Prophet Muhammad ﷺ, Muslims had expanded the empire into Spain and India.