How did the Crusades help open trade routes between Europe and the Middle East? 10 points per answer

Trade in much of Europe declined after the fall of Rome, and towns and cities declined in size, roads were not safe, and feudal manors were an important and self sufficient unit. Urban life remained active in the east, where cities grew especially with the rise of Islam, when Muslim societies though not unified in a single empire spread from the borders of China to the Iberian Peninsula in Europe on the Atlantic and Mediterranean.
The Crusades did not mark the beginning of trade between Muslim and Christian lands in Europe. Italian merchants traded across the Mediterranean with Constantinople, Syria and Egypt, and Spanish Muslims and Christians traded actively and produced fine goods for sale. Sicily, under Muslim rule and then under Norman rule, was a source of contact and production of goods. Among the most precious articles of trade were metal wares, silk textiles, and glass, as well as some food stuffs, dyes and perfumes.