The Khalid Nabi Cemetery is one of Iran’s most mysterious ancient sites. It is located in a mountainous region in the northeastern province of Golestan, near the border with Turkmenistan, and is nestled in the Gokcheh Dagh hills of Turkmen Sahra. These stunning green hills are also known as the “Valley of Genitalia.” Why? Because they are dotted with hundreds of headstones distinctly resembling male and female genitalia. Those believed to represent men are 1 to 5 meters tall, cylindrical in shape and capped, while those believed to represent women are shorter and rectangular in shape, with two upper lobes.

The cemetery’s origin is unknown, and little scholarship has emerged about it in Iran, for obvious reasons. There are no engravings on the phallic tombstones. They are believed to belong to the of the Turkmen tribes in northeastern Iran, who lead a nomadic existence and make a living training horses. Some experts suggest that the site is an ancient burial ground established more than 1,000 years ago by phallus worshipers from Central Asia and India.

The cemetery got its name from the nearby shrine of Khalid Nabi, which is said to house the tomb of Khalid bin Sinan, a Christian prophet born in Yemen in circa 530 A.D. — four decades before the birth of the Prophet Mohammed. Khalid Nabi’s mausoleum is a place of religious pilgrimage where the Turkmen come to seek resolution for their troubles by placing ribbons on his shrine. Two other holy shrines are also located near Khalid Nabi’s mausoleum: those of Alam Baba and Choupan Ata, both of which are revered by local Turkmen tribes.

The Khalid Nabi cemetery first came to prominence through an article published in 1981 by David Stronach, a Scottish archeologist who ran the British Institute of Persian Studies in Tehran starting in 1961. Stronach noted over 600 standing stones of unknown origin, many of which were clear representations of the phallus, on a mountain ridge located about a kilometer from Khalid Nabi’s mausoleum.

The site has since become a popular tourist destination, despite its rough terrain and inaccessible paths. Though it has been declared a national heritage site, the authorities have shown little interest in preserving and developing it.