After Chin Shih Huang sent Shu Fu to find medicine to prolong his life, in every subsequent dynasty people were sent to explore the ocean. The best known voyages are those of Fah Shean in the Northern and Southern Dynasties and Cheng Ho in the Ming Dynasty. Despite poor communications and inadequate equipment, both of these courageous adventurers completed their voyages successfully; in the process they promoted cultural exchange between China and the nations of the west. Fah Shean and Cheng Ho also made a great contribution to the promotion of trade between China and the countries on the periphery of the South China Sea.