In 1967, a farmer in Malawi stumbled upon a hidden cache of eight copper ingots buried beneath a tree. More than 50 years later, scientists have traced the origin of the metal to a copper mine nearly 800 km (500 miles) away. The findings, published in the Journal of Archaeological Science: Reports, reveal how Iron Age traders in southern Africa transported copper over long distances, using methods that resemble modern business decisions. Rather than taking a direct but challenging overland route, traders likely chose a longer but safer path by canoe, traveling down major rivers. Of the eight ingots found in the late 1960s, only five remain, with the other three missing. These ingots are similar in style to other X-shaped ingots found in Zambia and Zimbabwe, dating from the 14th to 18th centuries. However, they are unusual in that they are lighter and rougher than most other ingots. Researchers discovered that these ingots were not made by trained metalworkers. Instead, they were created by pressing normal ingots into moist sand, which left a rough mold that could not capture the finer details of a standard ingot. This method allowed for the quick production of thinner copies, though the purpose of burying them remains unclear. The location of the find, near Chombe in Malawi, is also significant. Malawi has no copper ore deposits, meaning the ingots must have come from elsewhere. Small deposits in neighboring Mozambique are unlikely to be the source, as their use was limited. Other potential sources include the world's largest copper ore deposits in the Copperbelt, located on the border between Zambia and the Democratic Republic of the Congo (DRC), and the old Kipushi mine near Lubumbashi in the DRC. Using lead isotopes, researchers matched the ingots to the Kipushi deposit, confirming their origin. The study suggests that traders used a river route more than 1,000 km (620 miles) long to transport the copper. The route likely started at the copper mines in what is now the DRC, then followed the Kafue River by canoe, moved east along the Zambezi River, and continued overland through Mozambique into central Malawi. This was not a random path but a carefully planned supply chain, developed centuries before the term "logistics" was used. The Chombe hoard may have been a stop along this trade route, serving as a midpoint between the Copperbelt and the capital of the Maravi state in Malawi. The findings also support Chewa oral traditions, which claim that the founders of the Maravi state migrated from the Copperbelt. "Malawi has always been a trading nation," said Smeda Matundu, chief curator of the Chichiri Museum. "Our geography, far from being a disadvantage, was once navigated brilliantly by traders who moved goods across nearly 1,200 km (750 miles) using nothing but rivers, footpaths and ingenuity."