Spices were one of the most profitable items of commerce known to man at this time. After the last of the Muslims were expelled from Spain, Spain and Portugal set out to enter "The Spice Trade".
Spain failed to get halfway to the "Spice Islands" so they ended up sponsoring Christopher Columbus whose idea was to reach the East by heading West.
I've got an idea! Instead of heading east to reach the east, we head west!
I can see land ahead!
We need to get to the Spice Islands as fast as possible!
I now hereby name you as an Indian!
Umm, this is America..
When the truth was realized, that an unknown, spiceless continent was blocking the route, a whole industry sprang up trying to find a way around it. This was called "Searching For The Northwest Passage"
But how do we make our way around this spiceless continent?
Yes! We can't let anyone get there before us! The Spice Islands are ours!