They needed to find an alternative to the Silk Road due to the rise of Ottoman Empire.
Explanation:
Ottomans seemed to be superior in owing the best naval fleet and it is always a threat to the Christian hegemony in Europe. The capital of Ottomans was Istanbul and it was five times the size of Paris in France. It flourished in abundance of natural resources. Ottomans were the largest army in Europe and the shipping lanes of the Mediterranean waterways were dominated by the ottomans.
They were in good trade relationships with Asian though the Silk Road and that insisted Europe to find an alternative to the Silk Road so that they would involve in trading ties with Asian countries. After the battle of Vienna, ottomans faced the decline.