Nestled in the mountains of Iraq’s Kurdistan Region, the Rabana-Merquly fortress has long mystified archaeologists. The site—constructed mainly during the first century B.C.E. and occupied intermittently for hundreds of years—features towering rock reliefs of an ornately attired ruler, whose identity is unknown.
A new study, published this week in the journal Antiquity, suggests that this figure was a king of Adiabene, a vassal state of the powerful Parthian Empire. If that’s the case, write the researchers, the fortress could very well be Natounia (or Natounissarokerta), a long-lost city named after the Adiabene dynasty’s founder, Natounissar, and only known to exist through a trove of first-century B.C.E. coins.
“[T]here are [not] any detailed historical references” to Natounia, lead author Michael Brown, an archaeologist at Heidelberg University in Germany, tells Artnet’s Sarah Cascone. “Rabana-Merquly is … the largest and most impressive site of the Parthian era in the region, and the only one with royal iconography, so it’s by far the best candidate.”
Brown and his colleagues tentatively identified the ruler as Natounissar based on similarities between the Rabana-Merquly reliefs and a statue of an Adiabene king in the city of Hatra, just over 140 miles west. Per the study, both depictions boast distinctive fin-shaped headwear, full beards, a raised right arm whose palm is open in “a gesture of salutation,” belts with hanging tapered ends, sleeveless cloaks and neck rings. The main difference between the artworks is the presence of a sword resting on the Hatra statue’s left hip.
“The twin rock reliefs are rare examples of near life-size monuments of rulers from the Parthian period, and they allow us to link the fortress with those who built it,” Brown tells Live Science’s Jennifer Nalewicki.
Another key piece of evidence comes from the coins, which give the lost city’s name as Natounissarokerta—a combination of the king’s name and the Parthian word for a moat or fortification. The coins describe Natounia’s location as “on the Kapros,” or the modern Lower Zab River.
“This description could apply to Rabana-Merquly,” which is situated along a tributary of the Lower Zab, says Brown in a statement.
According to the statement, the site consists of 27-foot-long fortifications and the smaller settlements of Rabana and Merquly. Drone mapping, as well as excavations conducted in 2009 and between 2019 and 2022, have revealed an array of structures, including military barracks and a religious complex that may have been dedicated to Anahita, the Persian goddess of water, fertility, health and healing.
As Brown tells the National’s Paul Carey, “The latest work is significant because we now understand that all the various archaeological features in the area—castle, rock reliefs, sanctuary—are parts of a single massive fortified settlement. Before, some parts were known but we didn’t understand the relationship.”
The researchers argue that Rabana-Merquly fulfilled multiple purposes, acting as a military fortress, trading hub, religious sanctuary, diplomatic center and “place of refuge in times of crisis,” as Brown tells Vice’s Jordan Pearson.
“The considerable effort that must have gone into planning, building and maintaining a fortress of this size points to governmental activities,” the archaeologist adds in the statement.
Though the evidence identifying Rabana-Merquly as Natounia is “circumstantial,” Brown tells CNN’s Katie Hunt that the site is the most promising possibility for the lost city, “which has to be in the region somewhere.”