Its commander was, without question, the most towering maritime figure in the 4,000-year annals of China, a visionary who imagined a new world and set out consciously to fashion it. He was also a profoundly unlikely candidate for admiral in anyone's navy, much less that of the Dragon Throne.
The greatest seafarer in China's history was raised in the mountainous heart of Asia, several weeks' travel from the closest port. More improbable yet, Zheng was not even Chinese—he was by origin a Central Asian Muslim. Born Ma He, the son of a rural official in the Mongol province of Yunnan, he had been taken captive as an invading Chinese army overthrew the Mongols in 1382. Ritually castrated, he was trained as an imperial eunuch and assigned to the court of Zhu Di, the bellicose Prince of Yan.
Within 20 years the boy who had writhed under Ming knives had become one of the prince's chief aides, a key strategist in the rebellion that made Zhu Di the Yongle (Eternal Happiness) emperor in 1402. Renamed Zheng after his exploits at the battle of Zhenglunba, near Beijing, he was chosen to lead one of the most powerful naval forces ever assembled.
Six centuries later I left China with photographer Michael Yamashita in search of Zheng He's legacy, a 10,000-mile (16,093-kilometer) journey that would carry us from Yunnan to Africa's Swahili coast. Along the way I came to feel that I had found the man himself.