A dakhma (Persian: دخمه), also known as the Tower of Silence, is a circular, raised structure built by Zoroastrians for excarnation–that is, the exposure of human dead bodies to the elements for decay in order to avert contamination of the soil with the corpses. Carrion birds, usually vultures and other scavengers, would typically consume the flesh and the skeletal remains would have been left in the pit.
Zoroastrian exposure of the dead is first attested in the mid-5th century BCE Histories of Herodotus, but the use of towers is first documented in the early 9th century CE. The doctrinal rationale for exposure is to avoid contact with Earth, Water, or Fire, all three of which are considered sacred in the Zoroastrian religion.
One of the earliest literary descriptions of such a building appears in the late 9th-century Epistles of Manushchihr, where the technical term is astodan, "ossuary". Another technical term that appears in the 9th/10th-century texts of Zoroastrian tradition (the so-called "Pahlavi books") is dakhmag, for any place for the dead.