Zheng He's western voyages took place during the first three decades of the 15th century, a period that marked the beginning of the Age of Maritime Exploration in both East and West. In Asia, Zheng He led his great fleets into the seas west of China, while in Europe, Prince Henry the Navigator sailed south from Portugal to explore the west coast of Africa. This great development signified that after thousands of years of coastal seafaring, humanity had finally recognized of the vast potential of the open ocean. The voyages of this period were the outcome of this new awareness. Of course, the great Chinese and European maritime explorers were products of their unique social conditions. As humanity turned its vision to the seas in the early 15th century, Zheng He's seven voyages, undertaken before the invention of any type of mechanical propulsion and into largely uncharted waters, were truly exceptional feats.