Why might the region of South Asia be referred to as "a land of great variety"?

South Asia has a great deal of variety in a number of
ways.

For example, South Asia is home to a variety of
physical environments.  You have, for example, jungles in India, the Himalaya mountains,
and the deserts of Afghanistan, all of which are in South
Asia.

As another example, you have a variety of religions
in this area.  You have Hinduism and Jainism and Sikhism, all centered in India.  You
have Islam in Indian and Pakistan and Afghanistan as well as other places.  You have
Buddhism, which started in India and is still practiced in some areas of Nepal, for
example.

There is also a great deal of ethnic diversity in
this area with all sorts of ethnicities in India, in Pakistan and in
Afghanistan.

In all of these ways, South Asia is a land of
great variety.