Between 1405 and 1433, the Ming dynasty of China carried out one of the most extraordinary maritime projects in pre-modern history. Under the Yongle Emperor, the imperial court launched seven massive expeditions across the Indian Ocean. They were commanded by a Muslim eunuch admiral named Zheng He.

The largest of these voyages involved more than 300 ships and roughly 28,000 men. The flagships were called treasure ships. Chinese records describe them as several times the length of any European vessel of the same period, though the exact dimensions are still debated by historians. The fleet reached Vietnam, Java, Sumatra, India, Sri Lanka, the Arabian Peninsula, and the east coast of Africa as far as present-day Kenya. They returned to China with giraffes, ostriches, precious stones, and ambassadors from dozens of foreign courts.

Then the policy was reversed.

After the death of the Yongle Emperor and the eventual death of Zheng He himself around 1433, a faction of Confucian scholar-officials at the imperial court argued that the voyages were extravagant, militarily unnecessary, and contrary to traditional Chinese inland values. Subsequent emperors agreed.

The voyages stopped. Later emperors imposed strict bans on the construction of ocean-going ships. The shipyards were dismantled. The official archives of the seven voyages were ordered destroyed or hidden away, and most of the documentation was lost. Some historians believe court officials, including a senior figure named Liu Daxia, destroyed records later in the fifteenth century to prevent any future revival of the policy.

Within a few decades, the world's largest blue-water navy had ceased to exist.

Sixty years after the last Zheng He voyage, three small Portuguese ships under Vasco da Gama rounded the Cape of Good Hope and reached India by sea.