Why was Christopher Columbus searching for India?

Christopher Columbus sought to secure new trade routes to the riches of Asia. India and Cathay (China) were important because they provided Europe with herbal medicines, perfumes, and silk. Also, Asia was the source of spices—used to preserve food and make it more delicious.
Gaining direct access to the products of Asia was problematic, however. Constantinople fell to the Muslims in 1453, and overland trade routes between Europe and Asia were long and difficult. Portugal began to reach India by sailing south around Africa and then north, and this was achieved by 1498. Portugal's adversary, Spain, supported Columbus in his effort to reach India by sailing west.
Columbus did not know that North and South America were located between Europe and Asia. He also underestimated the distance between Europe and Asia. The indigenous peoples he met on his voyages were named Indians because he mistakenly thought he had reached Asia. Columbus never fully understood that he had reached a new continent and not Asia.