An archaeological dig in France uncovered over two dozen dead horses and left researchers with a puzzling mystery. 

The excavation, located in Villedieu-sur-Indre in Central France, uncovered several buildings, pits, ditches and even a pathway from the early Middle Ages, according to a news release from the country’s National Institute for Preventive Archaeological Research. The finds included nine pits containing the remains of horses. 

Archaeologists used radiocarbon dating to determine that the horses lived between 100 BC to 100 AD, a span of about 200 years. 

Just two of the pits have been fully excavated so far. In one pit, the horses were all found lying on their right sides, with their heads to the south, according to the news release. The animals were “carefully placed in the pit and organized in two rows and on two levels,” and evidence shows that the horses were “buried simultaneously, very quickly after their death.” All the horses were small males, over four years old and likely Gallic livestock.  

The second pit contains just two horses, but they were buried the same way as the others.

Another pit was found to contain two adult dogs, positioned and “carefully placed” in the same fashion, the news statement said, but researchers don’t know what — if anything – the canine inclusion signifies. While other pits have yet to be excavated fully, researchers have found remains of bones that have allowed them to identify at least 28 horses buried in the site. 

The precision and uniformity of the burial sites have left researchers wondering how and why the animals died. According to the news release, illnesses can be ruled out since there are no young or female horses among the dead, leaving just two likely options: the horses may have fallen in battle and been buried with honors, or they may have been sacrificed. 

Similar discoveries have been made at other Gallic battle sites in France. One had a pit that held eight riders and their horses, while another site had 53 horses buried across five pits. The sites are close to battlefields in the region, making it possible that they were killed in those battles and buried, according to the news release.

Little information was given as to why the animals might have been sacrificed, with the news release noting that the death of 28 horses was a “massive drain on the heart of a herd.”

Researchers are continuing to study the pits and other structures at the site to try and answer how and why the animals died and what else the site may have been used for.