Rare hoard of Roman-era coins discovered in German mountains — miles from the empire's frontlines...

A metal detectorist in Germany has discovered a rare hoard of almost 3,000 Roman-era coins outside of the Roman Empire's ancient borders and far from any known Germanic tribe settlements of the time. Experts don't know how or why the huge hoard ended up there.

The licensed metal detectorist immediately reported the findings to government archaeologists in Koblenz, a city on the Rhine River. The subsequent excavation uncovered about 2,940 coins as well as more than 200 thin silver fragments decorated with geometric designs buried in a now-broken ceramic pot hidden between two rocks.

"Most of the coins are so called Antoniniani, which were the official silver coin in the Roman Empire in the 3rd century [A.D.] but mostly consisted of bronze with a thin silver overlay," Timo Lang, head of the Koblenz branch office of the State Archaeology in Rhineland-Palatinate who oversaw the excavation, told Live Science in an email.