A Dakhma also called a Tower of Silence, is a circular, raised structure built by Zoroastrians for excarnation – that is, for dead bodies to be exposed to carrion birds, usually vultures.
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 BCE. The doctrinal rationale for exposure is to avoid contact with Earth or Fire, both of which are considered sacred in 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. This Zoroastrian Middle Persian term is a borrowing from Avestan dakhma, of uncertain meaning but related to interment and commonly translated as "grave". In the Avesta, the term is pejorative and does not signify a construction of any kind. In the Iranian provinces of Yazd and Kerman, dakhma continues as deme or dema. Yet another term that appears in the 9th/10th-century texts is dagdah, "prescribed place".