Final answer:
During the Ming Dynasty, Nanjing served as the capital for six emperors. The longest reigning emperor was Emperor Yongle (Zhu Di), who ruled for 22 years.
Step-by-step explanation:
During the Ming Dynasty, Nanjing served as the capital for a total of six emperors. These emperors were:
Emperor Hongwu (Zhu Yuanzhang) from 1368 to 1398
Emperor Yongle (Zhu Di) from 1402 to 1424
Emperor Hongxi (Zhu Gaozhi) in 1424
Emperor Xuande (Zhu Zhanji) from 1425 to 1435
Emperor Yingzong (Zhu Qizhen) from 1457 to 1464
Emperor Jingtai (Zhu Qiyu) from 1449 to 1457
The longest reigning emperor of the Ming Dynasty was Emperor Yongle (Zhu Di), who ruled from 1402 to 1424. He had a reign of 22 years.