India and the adjoining countries are considered to be a subcontinent as it is comprised of all the characteristics of a continent.
Indian sub-continent encompasses vast areas of diverse landmasses. Indian sub-continent is comprised of lofty mountains, fertile plains, desert and plateau.
There is also great vastness and diversities in terms of climate, natural vegetation, wildlife and other resources.
Also, the vivid characteristics of culture and tradition among the people make it a sub continent.