The European try to find out an alternative sea route to India Because itbecame necessary for the Europeans to a direct sea route to the East because of the increase in demands of cotton, silk and spices. This resulted in great competition and less profit. Therefore, in order to gain profit the European had to and a cheap source of supply for these product.

Mainly to avoid paying the Muslims.

India has had ancient trade networks with Europe that goes earlier than the Greek and Roman civilizations [as a part of theTin trade]. Europeans have been visiting India for thousands of years and Indians have been doing the opposite trip.

While many Indians know that Europeans came to India, they don't know that the opposite happened too. There is the interesting story ofZarmanochegas- a Sramana philosopher sent by the Pandyan Kingdom of Tamil Nadu - who immolated himself in Athens 2000 years ago to prove his conviction to his philosophy. His tomb is still there in Greece. He and other philosophers brought Indian ideas to the West. This was instrumental in the development of Christianity [Buddhist influences on Christianity].