An unprecedented grouping of rare bipyramidal ingots has been discovered in the Sava River in Tolisa, northeastern Bosnia and Herzegovina near the border with Croatia. This shape of ingot dates them to between the La Tne culture and the beginning of the Roman era, the 2nd or 1st century B.C., and is exceptionally rare in the Balkans. Only one other example is known in Bosnia, one in Croatia, no more than three in Slovenia. They are more often found in France and Germany, but theyre still rare enough that the large number found in the Sava exceeds the total number of all such ingots known in Europe.The first glimpse of the ingots under water was caught by a local history buff. He took pictures and sent them to the director of Croatias Vinkovci City Museum who recognized them as important artifacts. Archaeologists with the Museum of the Franciscan Monastery of Tolisa Gate cooperated with a Croatian underwater archaeologist to investigate the find as soon as water levels dropped.The team found hundreds of ingots, making the site the richest source of them in European history.Based on the location and context, the researchers believe the iron cargo may have sunk as a result of a river accident perhaps due to a natural disaster or conflict and the heavy objects were stored in the sediment for centuries.To create a detailed 3D model of the find site, archaeologists used mapping and photogrammetry techniques, and each item was lifted, described, and placed in distilled water for preservation.To trace the origin of the iron, the scientists plan to study the chemical composition of the artifacts. This will help in mapping ancient trade routes that likely connected Bosanska Posavina with Central Europe. []The discovery not only reveals the role of the Sava River in ancient trade, but also elevates Bosanska Posavina to the status of a key location in prehistoric economic history. The researchers suggest that the discovery may prompt a rethinking of the regions significance in the wider context of European archaeology.