During Islam's Second Jihad, Muslim forces invaded Central Asia and defeated Constantinople in 1453, cutting off the overland route for Europeans. Islamic armies continued their jihad northward, and conquered much of what is now Eastern Europe, until they were stopped at the gates of Vienna in 1683.
Europe had been trading with the Far East for centuries, and their old overland route now went through territory that was hostile and dangerous to anybody but Muslims. The economy of Europe was threatened with ruin.
So, in 1492 (the year the Moors were defeated, ending the 780-year Muslim occupation of Spain) Columbus set off to find a passage to the Far East (financed by Spain) by boldly sailing West into the unknown. Desperate times call for desperate measures.
What he discovered changed the world.