The Indian subcontinent would be referring to the countries of India, Pakistan, Bangladesh, Sri Lanka, Maldives, and maybe Bhutan.

To me, it seems to me like this region has all the necessary element needed to count as a continent.

• Clear natural barriers seperate it from the rest of Asia
• Distinct, but highly diverse cultures and history
• Large population (more than all of Africa, and more than twice as much as Europe)

In fact, I think it has a better claim as a continent than Europe, since the Indian subcontinent actually used to be its own continent when it detached from Africa.