Elephants are found in Asia and Africa. Asia has three sub species of elephants. Scientific name of Indian elephant is Elephas Maximus Indicus. Indian female elephants do not have tusks.
I do not know about African Elephant but why elephants were not found everywhere? Why in India? Actually it has to do with food. Favorite food for elephants is leaves of sacred fig or peepal tree. This is how its leaves look like:

Apart for Peepal it is also called Bodhi Tree as Gautam Buddha attained nirvana under such tree. Meditation under this tree is very popular. Some worship it too. It has medicinal properties too, in Ayurveda. There is also a perceived taboo against cutting this tree for some. It is treated as King of trees. But it is the most persistent tree. It grows up at all unimaginable places. How seed travels to such places is unbelievable. It grows in cracks of walls, roof tops and everywhere. See this picture:

Here this tree is growing inside another tree’s trunk. This is translucent dried leaf of the same tree:

Below is a bodhi tree in a temple on the banks of Sangam (inside Allahabad Fort) and I wonder how old it must be? 200 years or more?

The conclusion is that for an animal weighing upto 5000 Kg. regular nourishment is necessary. Presently every Gardner is busy pulling small plants of this tree from here or their lest it may become too big. Look here is such problem:

They have cut the trunk from above but tree started to grow again. Now wall is being broken to pull the roots out. With such persistent growth, this tree is ideal feed for elephants. No wonder elephants were found in abundance in India.