Zheng He was a Chinese mariner, explorer, diplomat, fleet admiral, and court eunuch during the early Ming dynasty often regarded as the greatest admiral in Chinese history. He was originally born as Ma He in a Muslim family and later adopted the surname Zheng conferred by the Yongle Emperor. Commissioned by the Yongle Emperor and later the Xuande Emperor, Zheng commanded seven expeditionary treasure voyages to Southeast Asia, South Asia, West Asia, and East Africa from 1405 to 1433. According to legend, his larger ships carried hundreds of sailors on four decks and were almost twice as long as any wooden ship ever recorded.

A eunuch is a male who has been castrated. Throughout history, castration often served a specific social function. The earliest records for intentional castration to produce eunuchs are from the Sumerian city of Lagash in the 2nd millennium BCE. Over the millennia since, they have performed a wide variety of functions in many different cultures: courtiers or equivalent domestics, for espionage or clandestine operations, castrato singers, concubines or sexual partners, religious specialists, soldiers, royal guards, government officials, and guardians of women or harem servants.