Archaeologists have uncovered two rare Viking boat graves in the Swedish village of Gamla Uppsala.

One of the boats is intact, still holding the remains of a man, a horse and a dog.

Experts from Arkeologerna, archeologists with Sweden’s National Historical Museums agency, believed it would be a routine dig, so they were were shocked to find the two ships, the group’s Ninna Bengtsson said.

There are only about 10 other known boat burial sites like this in Sweden, Arkeologerna said. Ship graves of this kind were generally used in the Vendel Period, from about A.D. 550 to 800, and the Viking Age, from about A.D. 800 to 1050.

Most people at the time were cremated, with these sorts of boat burials reserved for society’s elite.

“It is a small group of people who were buried in this way. You can suspect that they were distinguished people in the society of the time since burial ships in general are very rare,” archeologist Anton Seiler said in a news release.

In this sort of burial, the person was placed along with his or her riches in a boat that was then put into the ground.

The archaeologists also found a sword, an ornate comb, a spear and part of a shield in the intact boat. The identity of the man remains unknown.

The other of the two boats did not hold up as well. It was probably damaged during work on the land in the 16th century.

The group began excavation on this site last fall but was forced to take a break in the winter due to cold weather. They restarted the process in June and are working to move the artifacts to a facility for further investigation.

It’s been 50 years since the last burial ship was found in Sweden, according to Seiler.

“It is extremely exciting for us since boat burials are so rarely excavated,” he said. “We can now use modern science and methods that will generate new results, hypotheses and answers.”