ACCORDING to the records, Australia was first discovered by Dutch explorers in the early 17th century. So how did 1,000-year-old copper coins from a former African sultanate end up on a remote Australian beach?
An Australian anthropologist, Ian McIntosh, is determined to get to the bottom of the mystery, which began when five coins were found buried in sand by a soldier patrolling the Wessel Islands off the continent's north coast in 1944, two years after Darwin was bombed by the Japanese.
Maurie Isenberg, who was manning a radar station on the uninhabited but strategically important islands, stored the coins in a tin, and on coming across them again in 1979, sent them to a museum.
They were identified as originating in the former sultanate of Kilwa, near present-day Tanzania, and dated to as far back as the 900s.
So far, so mysterious, for according to the history books the first outsider to set foot on Australian soil was a Dutchman, Willem Janszoon, who landed in present-day north Queensland in 1606 - more than 160 years before Captain James Cook arrived and claimed the continent for the British throne.
Dr McIntosh believes that the coins, which have apparently been gathering dust in the museum, could rewrite Australian history, indicating that the country was visited long before Europeans arrived.
In July he will lead a team to the Wessels, armed with a map on which Isenberg marked the spot where he found the coins with an "X".
"This trade route was already very active a very long time ago, and this may [be] evidence of that early exploration by people from East Africa or from the Middle East," he said.
According to Dr McIntosh, who is currently based at Indiana University in the US, the copper coins were the first produced in sub-Saharan Africa and have only twice been found outside the continent: in Oman in the early 20th century and in Australia by Isenberg, who was fishing off a beach at the time.
Dr McIntosh's team - comprising Australian and American historians, archaeologists and geomorphologists (scientists who study the shaping of landforms), as well as Aboriginal rangers - has confirmed that the coins date from between the 900s and 1300s.
At the same spot, the young soldier also unearthed four coins originating in the Dutch East India Company, one dating back to 1690.
Janszoon's visit was followed by that of a fellow Dutch seafarer, Dirk Hartog. But neither man - nor the Spaniard Luiz Vaez de Torres, who discovered the strait between New Guinea and Australia in 1606 - realised they had found terra australis (southern land), the hypothetical continent marked on world maps of the day as a counterweight to the north's landmasses.
Now a World Heritage ruin, Kilwa was once a flourishing trade port and in the 13th to 16th centuries had links to India. Its trade - in gold, silver, pearls, perfumes, Arabian stoneware, Persian ceramics and Chinese porcelain - made it one of the most influential towns in East Africa.
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