Bulgarian archaeologists have found two unique ceramic figurines of a cobra and dragon heads as they continue excavation at the rock sanctuary of Perperikon, near Kardzhali in southern Bulgaria.

The two figurines were part of the ornaments of a clay altar dating roughly to the period between the 3rd and 1st centuries before Christ, said archaeologist Nikolai Ovcharov, who oversees the dig.

The finds are probably part of the Tsepina culture, named after one of the key Thracian fortresses in the Rodopi Mountains, which played an important strategic role well into the medieval era.

The two finds are more important than the Roman era finds because they offer much more insight into the distinctive traits of the local culture, Ovcharov said.

Snakes were considered guardians of the deeps and, as such, were closely associated to the cult of Dionysus, whose shrine the Bulgarian archaeologists are currently excavating.

The next stage of the dig, which is staffed by close to 150 people, is to examine the southern quarter of the city, where the archaeologists hope to remain the remains of a third palace, dating back to the Thracian era.

The city of Perperikon has been inhabited since around 5000 BC, while a nearby shrine dedicated to Orpheus, near the village of Tatul, dates back to 6000 BC and is older than the Pyramids of Giza.