Reporter: Now can you explain to me, I have some background information about the Krishna consciousness society, but I don't know how to explain it in relation to the broad word Hinduism. Now how do you relate the International Society for Krishna Consciousness to Hinduism? How would you describe it, as a part of Hinduism? 

Srila Prabhupada: No. Hinduism practically we do not recognize because this word "Hinduism" is not mentioned in any Vedic literature. It is a foreign term. The Muhammadans, they called the inhabitants of India as "Hindus." From that word, it is has come to "Hinduism." Otherwise, we don't find that word in any Vedic literature. "Hinduism" is a foreign term, it is not a Vedic term. 

Reporter: Yes. The Krishna consciousness, its Vedic literature, they have some of the same books or also holy books for what we call Hindu religions, aren't they? 

Srila Prabhupada: Yes. Just try to understand, the inhabitants of India were called by the Muhammadans from Persia and other places, "Hindus." "Hindus" means the resident on the other side of the River Indus. You have heard the name of River Indus. So they cannot pronounce it Indus, they say "Hindus." From "Hindus," it has become "Hindu." So actually the residents of India were called "Hindus." And generally, at least in, say, three thousand years ago, all the inhabitants of India were strictly followers of Vedic principles. After the advent of Lord Buddha, a different religious system developed. Otherwise, before Lord Buddha, there was all the… Not only in India, in other parts of the world. They were followers of Vedic principles. So in that sense, you can say if followers of Vedic principles are called Hindus, then before Lord Buddha, everyone was Hindu all over the world. Not that particular part of India. So far we have got historical reference from Mahabharata, Indo-European stock, they are also Hindus, the so-called Hindus, followers of Vedic principles. Yes. Gradually, they deviated. Just like recently there is division of Pakistan and India. Twenty years before, this Pakistan was part of India. Now, these Muhammadans, they did not come from outside. They changed their faith from Hindus to Muhammadans. Now they divided their property. Similarly, actually the whole planet was called Bharata-varsa. Gradually, people deviated from Vedic principles or imitated something else and they became different.

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taken from here