BBC’s Mark Prigg’s reports that scientists have found a rare, 600-year-old coin from China on the Kenyan island of Manda. The discovery rewrites the history books on international trading.

Researchers say that the 600-year-old coin is a copper coin has a square hole in the center so it could be worn on a belt. It proves that trade existed between China and eastern Africa decades before European explorers set sail.

Scientists say Emperor Yongle of China who reigned from 1403-1425 during the Ming Dynasty issued it. The emperor’s name is written on the 600-year-old coin.

The discovery was through a joint expedition of scientists led by Chapurukha Kusimba of The Field Museum and Sloan Williams of the University of Illionois at Chicacgo. Scientists from Kenya, Pennsylvania and Ohio also participated in the expedition. The explorers have also discovered human remains and other artifacts predating the coin.

Emperor Yongle, who started construction of China’s Forbidden City, took interest in political and trade missions to the islands that ring the Indian Ocean and sent Admiral Zheng He, also known as Cheng Ho, to explore those shores.

Zheng He is in many ways considered the Christopher Columbus of China, according to Dr. Kusimba, Curator of African Anthropology at the Field Museum.

“It is wonderful to have a coin that may ultimately prove [Zheng He] came to Kenya,” Kusimba said.

The relationship, however, soon stopped after Emperor Yongle’s death when later Chinese rulers banned foreign expeditions, allowing European explorers to dominate the Age of Discovery and expand their countries’ empires, the researchers say.

Portuguese where the first Europeans to explore the region of current-day Kenya. Vasco da Gama visited Mombasa in 1498.

The coast of East Africa was a valuable foothold in the eastern trade routes, and Mombasa was a key port for ivory.

Modern European explorations of Kenya weren’t initiated until 1844. Two German missionaries, Johan Ludwig Krapf and Joahnnes Rebmann ventured into the interior of Mombasa with the goal of introducing Christianity.