Answer:
seek new trade routes to East Asia.
Step-by-step explanation:
After Byzantine Empire fell in the hands of Ottomans, the trade links between Europe and East were interrupted. Therefore, Portuguese and Spanish sailors decided to find a water route to East India.
Their first idea was to sail around Africa and to reach India. That was the idea of Portuguese, while Spaniards believed that by sailing towards the west they will reach eastern shores of Asia.