Past Masters, which is based in the northern Australian city of Darwin, posted an image of the coin on its Facebook page. It features Manchurian script, which was the native language of China's imperial Qing dynasty.
The coin's presence is hardly proof that a Qing fleet would have landed on Australia's shores, of course. It's far more likely it ended up on the island off the continent as part of a linked chain of Asian trade that threaded China throughout Southeast Asia. Traders from the island of Sulawesi, now part of modern Indonesia, have a long history of visiting northern Australia and harvesting sea cucumbers -- a delicacy Australian experts believe would have also interested Chinese merchants. Past Masters also points to indigenous oral histories that recount supposed dealings with Chinese visitors and the Aboriginal practice of using Chinese coins as fishing weights.
In the 1940s, archaeologists working in the same island chain off the coast of the Northern Territory discovered nearly 1,000-year-old coins minted in East Africa, a fascinating snapshot of a world of Indian Ocean trade that existed before the arrival of the Europeans.
European sailors first caught a glimpse of Australia beginning in the early 17th century, but it was only after Britain's Capt. James Cook made landfall in 1768 that European settlement of the continent began in earnest.
Another theory involving China has won attention in the past decade. "1421", a best-selling book by Gavin Menzies, a former British naval officer, suggests that the great 15th-century treasure fleets of the Ming dynasty, captained by the famed Muslim eunuch Zheng He, landed in Australia and even as far afield as the Americas. Most historians dismiss Menzies's claims as flimsy pop history, built on dubious evidence and fraudulent maps.
But the voyages of Zheng He have grown increasingly important in China's own national conversation, where the country's contemporary rise on the global stage, along with its expanding economic clout, is seen almost as a restoration of a benign imperial past, when Ming-era fleets could call on ports across the Indian Ocean. The Chinese have been involved in archaeological expeditions off the coast of East Africa to find further proof of their historic contacts with the region. Perhaps a similar effort in northern Australia may not be too far off.