The word “Yazd” is an ancient term, which is etymologically connected to the words “Yasht”, “Yazt”and “Yash”, all of which, in old Pahlavi language, reflected concepts such as, “prayer”, “worship”, and “deity” respectively. Also one, of the Avesta's five chapters is entitled “Yasht”.

According to Abdul Hossein Ayati, author of “Fire Temple of Yazdan”, the ancient city of Yazd had been named “Isatis”. “Kasa” was another name given to the region. It has been relayed that during the rule of Alexander the Great in Iran, Yazd was named Kasa after the city's first building, which later came to be known as the “Zulqarnain” or, “Alexander's prison”.

The word Yazd, however, is the latest name, which has been historically relayed to us today. In Sassanid era, the city was known as “Yazdan” or, “Yaztan”, which had religious roots. Some of the ancient texts have referred to Yazd as house of historian in 15th century AD. Seljuk King, Malekshah, gave the government of Yazd to Alaiddowleh in 1095 AD and named the city “Darul Ibadeh” (House of Pray).

By the arrival of Arab in Iran in 651 AD, Yazd region's people, like the peoples of other parts of Iran, were Zoroastrian. They had fire temples and their social rites and customs were shaped under the influence of Zoroaster's teachings.

Sassanid kingdom was toppled by Arab in 651 AD and the people of the central parts of Iran, including Yazd and its surrounding regions, embraced Islam in general, while some of them preferred to pay Jazieh(a religious tax to preserve their ancestors' religion) and remained Zoroastrian. Now, Yazd is the biggest center of Iranian Zoroasters.