A weathered, hand-drawn map, with an "X" marking the spot on the Australian island where the African coins were discovered, might help an international team of researchers, who will travel to the island this summer, answer that question.
The story begins over a thousand years ago, when the city of Kilwa was the richest trading center on the eastern coast of Africa.
A bustling harbor, a glittering mosque decorated with Chinese porcelain and the Husuni Kubwa palace (famed for its octagonal swimming pool) made Kilwa a premier destination for wealthy merchants, who traded African gold and ivorty for spices and perfume from the Far East.
A dazzling era ends
But the city's eminence ended when Portuguese traders, intent on controlling commerce throughout the Indian Ocean, sacked the port in the 16th century.
"The Portuguese destroyed Kilwa in the 1500s, burnt it to the ground and looted everything," Ian McIntosh, a professor of anthropology at Indiana University-Purdue University Indianapolis (IUPUI), told Australian broadcaster ABC.
The deserted, crumbling ruins of Kilwa — now a UNESCO World Heritage site located near Zanzibar in modern-day Tanzania — are all that remains of the city's former splendor.
A handful of coins
Centuries later and thousands of miles away, an Australian soldier named Maurie Isenberg was operating a World War II radar station on one of the uninhabited Wessel Islands off Australia's northern shore, CNN reports.
One day, during his off-hours, Isenberg went fishing down at the remote island's beach, where he discovered a few old, copper coins with exotic markings embedded in the sand. Isenberg tossed the coins in a tin container, where they stayed for decades.
But before he forgot about his discovery, on a map of the island hand-drawn by a fellow soldier, Isenberg drew an "X" showing where he found the coins.
In 1979, Isenberg sent the coins off for appraisal. He was astonished to discover their origin: Four of the coins were from the Dutch East India Company — a trading company founded by the Dutch in the early 17th century — and one of those coins dated from the late 1600s, according to CNN.
But five of the coins were minted in Kilwa and are believed to be about 1,100 to 1,200 years old (from about A.D. 900), ABC reports.
"It's a very fascinating discovery," McIntosh told CNN. "Kilwa coins have only ever been found outside of the Kilwa region on two occasions.
"A single coin was found in … Zimbabwe, and one coin was found in the Arabian Peninsula, in what is now Oman, but nowhere else," McIntosh said. "And yet, here is this handful of them in northern Australia — this is the astonishing thing."
Will 5 coins rewrite history?
The Eurocentric view of history holds that Australia, populated by Aboriginal settlers for some 60,000 years, was "discovered" by European explorers in 1606.
But since the discovery of the ancient coins, which came to the attention of McIntosh before Isenberg died in 1991, that history may need to be rewritten. McIntosh also has the old map showing where the coins were discovered.
This July, McIntosh will carry that map back to the Wessel Islands, where he's leading an international team of researchers intent on solving the mystery of how the coins found their way to a remote beach in Australia.
"We have five separate hypotheses we're looking to test about how these coins got there — each one quite different from the other," McIntosh told CNN.
Some speculate that the Portuguese sailed along Australia's northern shores much earlier than was previously known. Another hypothesis suggests that African sailors from Kilwa were hired by merchants from the Far East to navigate the seas of China.
"Once you shift from the Eurocentric focus — and this is how it could change Australian history — you start seeing north Australia as part of this ancient trading network which links southern Africa, Arabian Persia, India, the Spice Islands and China," McIntosh told ABC.
A cave of treasures
Adding to the adventure's appeal is an Aboriginal legend that mentions a hidden cave, located near where the coins were found, that holds a treasure of doubloons and weaponry from an ancient era, according to a news release from IUPUI.
Despite their rich history, the old copper coins — now in the Powerhouse Museum in Sydney — have limited financial value.
"If you bought these coins in a shop in Kilwa, you could probably get them for a few dollars," McIntosh told CNN. "But in northern Australia, these are priceless in terms of their historical value."
Lallanilla, Marc. 2013. “Ancient African Coins Spark International Treasure Hunt”. Live Science. Posted: June 26, 2013. Available online: http://www.livescience.com/37772-ancient-african-coins-kilwa-ian-mcintosh.html