INDIANAPOLIS, INDIANA—In 1944, while stationed on Australia’s Wessel Islands, soldier Maurie Isenberg discovered five 1,000-year-old copper coins thought to have been minted in the former Kilwa sultanate, a trading port on an island off the coast of Tanzania. Isenberg marked the spot where he found the coins on a map, and in 1979, donated them to an Australian museum. Now Ian McIntosh of Indiana University wants to know how the coins got to the northern coast of Australia. The coins may have washed ashore from a shipwreck, or there may have been maritime trading routes linking east Africa, Arabia, India, and the Spice Islands to Australia long before Europeans made the trip. McIntosh plans to excavate Isenberg’s site this summer.