A Circular Anomaly
In the Kyzylkum desert of Karakalpakstan, Koy-Krylgan-Kala presents a geometric puzzle. Unlike the typical square fortresses of ancient Khorezm, this structure is a perfect circle. The entire complex measures approximately 90 meters in diameter. It consists of a central two-story cylindrical building, 42 to 44.5 meters across, encircled by a formidable outer wall that was once up to 7 meters thick. Between the central building and the outer defenses, a ring of residential and utility buildings once stood. Nine towers were built into the defensive wall.
Construction began in the 4th century BCE and the structure is made of pakhsa (rammed earth) and adobe bricks. The central building's ground floor contains eight vaulted rooms arranged in a cruciform shape, which were likely used for ritual purposes. The upper floors probably stored temple utensils and food. The entire fortress was once surrounded by a moat 15 meters wide and 3 meters deep. This initial phase of use ended around the start of the 1st century AD when the site was destroyed, possibly by nomadic tribes or a major fire. It was later reoccupied and used as a fortified settlement until the 4th century AD.
An Astronomic Temple
The structure's design was for more than defense. Its layout suggests it was a Zoroastrian temple and astronomical observatory. Researchers believe the building was used for observing the sun and stars. Early studies proposed that the main axis of the building aligned with the rising of the star Fomalhaut. More recent analysis using satellite imagery suggests the primary axis, with an azimuth of 80 degrees, points to the heliacal rising of the Pleiades star cluster. The rising of the Pleiades in ancient Khorezm coincided with the third flood of the Amu Darya river, an important seasonal event.
Excavations have uncovered numerous artifacts related to Zoroastrian worship. The population venerated deities such as Anahita, a goddess of water, and Siyavush, a sun god. The western part of the complex may have been dedicated to Anahita, while the eastern and southern portions faced the sunrise in honor of Siyavush. Archaeologists found fragments of about 10 ceramic statuary ossuaries, boxes for holding human bones according to Zoroastrian ritual, some depicting male and female deities. Other finds include terracotta figurines, stone seals, and pottery fragments with inscriptions in the ancient Khorezmian language.