Fuzhou was in its day an important trading centre, visited by Marco Polo during the Yuan dynasty. In the fifteenth century, Fuzhou shipbuilders earned themselves the distinction of having built the world's largest ocean-going ship, the Baochuan, sailed by the famous Chinese navigator Zheng He, who used it to travel all around Asia and Africa. One thing Polo noted when he was here was the high-profile presence of Mongol armies to suppress any potential uprisings, and, by coincidence, the city is no less well defended today, forming the heart of Fujian's military opposition to Taiwan. Much like Xiamen farther south, it was the postwar tension between the Nationalists and the Red Army that contributed to Fuzhou's decline after the arrival of the Communists. Today, the proximity of Taiwan is contributing to the enormity of the city's economic boom.