In the middle of the 15th century (1450 AD) the spices and silk of Asia were reaching Europe through the Red Sea and North Africa. That was the sea part of the Silk Roads. I must add that at the time the British had not yet constructed the Suez Canal which later connected the Red and the Mediterranean Seas.
The commerce of spices and silk was controlled by Arab merchants at the East Mediterranean Sea, and from there by the merchants of Venice (see red dot on Italy at the following map). Therefore the Western Europeans had to pay the profits of the merchants from Venice and Egypt, and whatever duties and taxes had to be paid on top of these profits.
At the calm sea of the Mediterranean Sea the Portuguese ships could not confront the ships of the Venetians and the Ottomans which were larger and had more powerful cannons, but the Portuguese had an advantage at the oceans, because the Portuguese had more skills and their ships were easier to maneuver. The Portuguese started using the Atlantic Ocean and West Africa in order to open trade corridors, but their biggest success was when Vasco da Gama managed sail around Africa and reach India in 1499. In 1509 the Portuguese defeated the Ottoman navy near Diu of India (see red X on the map).
Therefore the Portuguese managed to keep a part of the trade of spices and silk around Africa and towards Western Europe, creating various strongholds on this corridor.