<P> Gan Ying, the emissary of General Ban Chao, perhaps traveled as far as Roman Syria in the late 1st century AD . After these initial discoveries, the focus of Chinese exploration shifted to the maritime sphere, although the Silk Road leading all the way to Europe continued to be China's most lucrative source of trade . </P> <P> The pilgrimage of the Buddhist monk Xuanzang from Chang'an to Nalanda in India not only greatly increased the knowledge of Buddhism in China--returning more than 650 texts including the Heart and the Perfection of Wisdom Sutras--and inspired the immensely influential novel Journey to the West . It also led to Xuanzang's publication of the Great Tang Records on the Western Regions, a text which introduced China to Indian cities such as the port of Calicut and recorded many details of 7th - century Bengal for posterity . </P> <P> Before the advent of the Chinese - invented mariner's compass in the 11th century, the seasonal monsoon winds controlled navigation, blowing north from the equatorial zone in the summer and south in the winter . This most likely accounts for the ease in which Neolithic travelers from mainland China could settle on the island of Taiwan in prehistoric times . After defeating the last of the Warring States and consolidating an empire over China proper, the Chinese navy of the Qin Dynasty period (221--207 BC) assisted the land - borne invasion of Guangzhou and northern Vietnam . (Called first Jiaozhi and then Annam, the northern half of Vietnam would not become fully independent from Chinese rule until AD 938 .) In 1975, an ancient shipyard excavated in Guangzhou was dated to the early Han Dynasty (202 BC--AD 220) and, with three platforms, was able to construct ships that were approximately 30 m (98 ft) in length, 8 m (26 ft) in width, and could hold a weight of 60 metric tons . </P> <P> During the Three Kingdoms, travellers from Eastern Wu are known to have explored the coast . The most important were Zhu Ying (朱 應) and Kang Tai, both sent by the Governor of Guangzhou and Jiaozhi Lü Dai in the early 3rd century . Although each wrote a book, both were lost by the 11th century: Zhu's Record of the Curiosities of Phnom (t 扶南 異物 誌, s 扶南 异物 志, Fúnán Yìwù Zhì) in its entirety and Kang's Tales of Foreign Countries During the Wu Period (t 吳 時 外國 傳, s 吴 时 外国 传, Wúshí Wàiguó Zhuàn) only surviving in scattered references in other works, including the Shuijing Zhu and the Yiwen Leiju . </P>

Why did china's sea explorations stop in the 1500s