A region on the eastern shore of the Caspian where chalk outliers stand in the desert like the ruins of cities, and ridges of perfectly round stone spheres emerge from the ground — concretions up to three metres across. Beket-Ata is here too, an underground mosque cut into a chalk hill by a Sufi preacher in the eighteenth century; a steady stream of pilgrims comes to it, and tradition requires the night before a visit to be spent in the neighbouring valley.