Illinois-based scientists discovered a 600-year-old Chinese coin on the island of Manda, off the East African coast, they announced Wednesday. (John Weinstein/The Field Museum)

Scientists have unearthed a 600-year-old Chinese coin in Kenya that they say proves trade existed between China and East Africa decades before the European explorers arrived.

The Ming Dynasty-era coin is copper and silver with a square hole in the centre that could be used to attach it to a belt. Researchers from Chicago's Field Museum and the University of Illinois found the ancient relic on the island of Manda, off the northern coast of Kenya, along with human remains and other artifacts older than the coin, they announced Wednesday.

"This finding is significant. 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," said Chapurukha Kusimba, curator of African anthropology at the Field Museum.

Around AD 1400, Chinese Admiral Zheng He led political and trade missions to foreign lands and was known as "the Christopher Columbus of China," Kusimba said.