After the collapse of the Mongolian Empire, the Ming dynasty came to power in China. Following the death of the first Ming emperor, one of his sons, the Prince of Yan, seized power from his nephew after a civil war and made himself emperor under the name of Yongle. The new Emperor Yongle, trying to revitalize China’s ailing economy, switched China’s currency from paper to silver. Abroad, he extended Chinese power by conquering Mongolian territory to the north and west, demanding subservience from Central Asian rulers and exerting influence over Annam (northern Vietnam). Additionally, he sent a massive expedition of ships into the Indian Ocean led by Admiral Zheng He. In a series of voyages, the fleet reached as far as Mozambique and the Spice Islands of Southeast Asia. Zheng He was himself a Muslim and established diplomatic relations with Islamic governments in Egypt and East Africa. However, China did not sustain this large navy. After Emperor Yongle’s death, China focused on protecting its northern border against the Mongolians rather than on patrolling the Indian Ocean and further ocean explorations. This change in Chinese policy likely made it easier for Europeans to take control of the Indian Ocean and colonize several coastal areas.