The centuries-old coins were first unearthed on a farm in the southern Hunan province in the 1960s, where they had been kept inside a small glazed pot. They arrived at Jinshi City's museum in the 1980s, and archaeologists have been puzzling over their markings ever since, the Xinhua news agency reports . Now the museum says it'll hand out 10,000 yuan ($1,500; £1,100) to anyone who can help to shed light on the meaning of the coins' etchings.