About 55 million years ago, plate tectonics made the land that is now India break off from what is now Africa. At this time, the first modern mammals like rats and guinea pigs were evolving, and most of the Earth was covered in forests.
For five million years India floated slowly away from Africa until, about 50 million years ago, India bumped into Asia. The force of this impact slowly pushed the land between them to fold up into big new mountains which we call the Himalayas. So at the very top of the Himalaya mountains you can find limestone that formed at the bottom of the ocean. Plate tectonics pushed the limestone up to the top of the mountain. The Himalayas are older than the Alps, but they're younger than the Rocky Mountains.
A video tour of the Himalayas
The Himalayas separate India from the rest of Asia, forming the border between India and China and between India and Central Asia. The word Himalayas comes from the Sanskrit phrase "home of the snow", because the Himalaya mountains are high enough to always have snow on them. They are the highest mountains in the world.
Even today, India is still slowing pushing against Asia, moving north about one centimeter every six months, and that is still pushing the land upward, so the Himalayas are still growing and getting higher and higher.