A joint expedition of The Field Museum and the University of Illinois at Chicago unearthed the 600-year-old coin on the Kenyan island of Manda, a release by the museum reported Wednesday.
The small copper and silver coin, with a square hole in the center so it could be worn on a belt, was issued by China's Emperor Yongle, who reigned from AD 1403-1425 during the Ming Dynasty, the researcher said.
Yongle initiated political and trade missions to the lands surrounding the Indian Ocean and sent Admiral Zheng He to explore the region, they said.
"Zheng He was, in many ways, the Christopher Columbus of China," Chapurukha M. Kusimba, the museum's curator of African Anthropology, said. "It's wonderful to have a coin that may ultimately prove he came to Kenya."
After Emperor Yongle's death later Chinese rulers banned foreign expeditions, allowing European explorers to dominate the Age of Discovery, the researchers said.
"We know Africa has always been connected to the rest of the world, but this coin opens a discussion about the relationship between China and Indian Ocean nations," Kusimba said.