By the mid-15th century, the Byzantine Empire had collapsed and the various Crusades that had taken place in the region had largely disrupted the overland routes of the Silk Road and trade. Compounding the difficulties of trade was the rise of the Ottoman Empire in place of the Byzantines and the outbreak of the Black Death in Europe. It was roughly around this time that a period of European exploration began, and major factors that contributed to this period of exploration were introduced by the Chinese, albeit indirectly. The magnetic compass had already been developed and used by the Chinese sailors since the 12th century, although it had first been created in the 3rd century B.C. as a divination device. The Song Dynasty then began using the device for land navigation in the 11th century and sailors began using it shortly after. The technology slowly spread west via Arab traders, although a case can be made for the independent European creation for the compass (Southey 1812: 210). Regardless, by the 13th century the compass had found its way to Western traders, coming at a time that trade had been increasing across Europe. Trade was able to increase in Europe around the world due to more effective ships being introduced, and some of the improvements that were made to the ships were first introduced by the Chinese. The introduction of multiple mast ships and the sternpost rudders allowed the ships to travel quicker and be more maneuverable. By the start of the 15th century, ships were now much larger and able to support long distance travel with a minimum number of crew aboard. One explorer, Christopher Columbus, sought funding from the Portuguese to search for a passage to Asia by sailing westwards, but he was rejected. However, Portugal's domination of the western African sea routes prompted the neighboring Crown of Castile and the Catholic monarchs in modern Spain to search for an alternative route to Asia.
