The last Muslim kingdom of Spain. It was seized by Ferdinand and Isabel being seen as one of the "problems" of 1492. Granada had a lot of Muslim influence (El Alhambra- a major region for trade and markets for European and luxury goods)
So Im guessing Europe
The Pope may have had a number of religious reasons to call this crusade. The most likely religious reason for the First Crusade was Urban's desire to establish peace in Western Europe. This whole concept may seem odd, since the Crusades were, essentially, a call to arms
Slaves were contributing to the Southern war effort by providing food, supplies, and manual labor.