Archaeologists made a gruesome discovery when they unearthed an ancient burial site filled with thousands of bones — later identified as victims of a battle fought 2,000 years ago in northern Europe between "barbarian" Germanic tribes.

The mass grave, located at the Alken Enge wetlands in Jutland, Denmark "provides the earliest direct archaeological evidence of large-scale conflict among the Germanic populations," a new study in the peer-reviewed journal "Proceedings of the National Academy of Sciences" (PNAS) explained.

The skeletal remains gave officials a clearer picture of little-known post-battle rituals in the Iron Age, revealing what winning sides did with fallen soldiers' bodies after the war. Crushed cranias, stripped bodies, cuts with sharp-edged weapons, the removal of the abdomen and intestines and the separation of bones are some of the most brutal practices noted in the paper.

"This was barbarian-on-barbarian." — Peter Bogucki, archaeologist

So far, the bodies of 82 individuals have been uncovered but authors of the study, which was published Monday, believe there are as many as 380 total dead bodies — mainly young adult males — buried in the wetlands.

"Taphonomic traces indicate that the bones were exposed to animal gnawing for a period of between 6 mo and 1 y before being deposited in the lake," according to the study. "Furthermore, the find situations, including collections of bones, ossa coxae threaded onto a stick, and cuts and scraping marks, provide evidence of the systematic treatment of the human corpses after the time of exposure."

The single day battle took place during the expansion of the Roman Empire. Many Romans at the time shared tales of the "ferocious" German tribes.

The majority of battles during that time period were between the Germans and the Romans. This one, however, appears to be different.

"This was barbarian-on-barbarian," Princeton University archaeologist Peter Bogucki, who did not contribute to the study, told National Geographic. "It's indigenously generated. This continues a pattern of endemic, intergroup violence in the region that goes back into prehistory."

The Germanic armies were good at hiding their tracks — only a few battle sites in Germany have been revealed, including the Battle at the Harzhorn in the early third century and the Battle of the Teutoburg Forest in Kalkriese in AD 9, the study states.

Bogucki believes the bodies were moved from the battlefield and transported into the nearby shallow lake several months later.

"This is 'memory work' after the battle," he commented. "They are deliberately trying to create some collective memory of the event."

Though the motivation behind the fight remains unclear, authors of the study believe it was started with the hope of "eradicating the military leaders, or was perhaps connected with the acquisition of slaves."

Several weapons such as spearheads, swords, shields and an ax were also found at the excavation site.

Researchers, particularly lead author of the study Mads Kähler Holst of Aarhus University in Denmark, plan to continue studying the remains in hopes of learning more about the ancient battle practices.

"The Alken Enge find is exceptional of the period, but it anticipates the comprehensive postbattle weapon depositions from the second to fifth centuries AD in Northern Germania," the study concluded. "In this way, Alken Enge provides a new, yet older, testament to the history of the militarization of the Northern Germanic societies and stresses the formative significance of the expansion phase of the Roman Empire at the turn of the era."