When Christopher Columbus sailed west and Vasco Da Gama sailed around Africa to look for new routes to India and China they were not just looking to find a more profitable route. They were looking for ANY route. With the rise of Islam around 610 AD and the Crusades starting around 1000 AD which cemented animosity between Christianity and Islam the eastern land route was closed off to the west.

(Book – The Last Crusade: The Epic Voyages of Vasco Da Gama  – Nigel Cliff)