Nowrūz (Persian: نوروز, IPA: [nouˈɾuːz], “New Day”, originally “New Light”) is the traditional celebration of the ancient AchaemenidIranian New Year. Nowruz is also widely referred to as the Persian New Year.
The celebration has its roots in Ancient Iran. Due to its antiquity, there exist various foundation myths for Nowruz in Iranian mythology. In the Zoroastrian tradition, the seven most important Zoroastrian festivals are the six Gahambars and Nowruz, which occurs at the spring equinox. According to Mary Boyce,[
|“||It seems a reasonable surmise that Nowruz, the holiest of them all, with deep doctrinal significance, was founded by Zoroaster himself.||”|
Between sunset of the day of the 6th Gahanbar and sunrise of Nowruz was celebrated Hamaspathmaedaya (later known, in its extended form, as Frawardinegan). This and the Gahanbar are the only festivals named in the surviving text of the Avesta.
The Shahnameh, dates Nowruz as far back to the reign of Jamshid, who in Zoroastrian texts saved mankind from a killer winter that was destined to kill every living creature. The mythical Persian King Jamshid (Yima or Yama of the Indo-Iranianlore) perhaps symbolizes the transition of the Indo-Iranians from animal hunting to animal husbandry and a more settled life in human history. In the Shahnameh and Iranian mythology, he is credited with the foundation of Nowruz. In the Shahnama,Jamshid constructed a throne studded with gems. He had demons raise him above the earth into the heavens; there he sat on his throne like the sun shining in the sky. The world’s creatures gathered in wonder about him and scattered jewels around him, and called this day the New Day or No/Now-Ruz. This was the first day of the month of Farvardin (the first month of the Persian calendar).
The Persian scholar Abu Rayhan Biruni of the 10th century A.D., in his Persian work “Kitab al-Tafhim li Awa’il Sina’at al-Tanjim” provides a description of the calendar of various nations. Besides the Persian calendar, various festivals of Arabs, Jews, Sabians, Greeks and other nations are mentioned in this book. In the section on the Persian calendar(تقویم پارسیان), he mentions Nowruz, Sadeh, Tiregan, Mehregan, the six Gahanbar, Parvardegaan, Bahmanja, Isfandarmazh and several other festivals. According to him: It is the belief of the Persians that Nowruz marks the first day when the universe started its motion. The Persian historian Abu Saʿīd Gardēzī in his work titledZayn al-Akhbā under the section of the Zoroastrians festivals mentions Nowruz (among other festivals) and specifically points out that Zoroaster highly emphasized the celebration of Nowruz and Mehregan.
Although it is not clear whether proto-Indo-Iranians celebrated a feast as the first day of the calendar, there are indications that both Iranians and Indians assumed the first day of autumn as the beginning of new year season. There are reasons that Iranians may have observed the beginning both autumn and spring.
Boyce and Grenet explain the traditions for seasonal festivals and comment:”It is possible that the splendor of the Babylonian festivities at this season led the Persians to develop their own spring festival into an established new year feast, with the name Navasarda ‘New Year’ (a name which, though first attested through Middle Persian derivatives, is attributed to the Achaemenian period). Since the communal observations of the ancient Iranians appear in general to have been a seasonal ones, it is probable, however, that they traditionally held festivals in both autumn and spring, to mark the major turning points of the natural year”.
We have reasons to believe that the celebration is much older than that date and was surely celebrated by the people and royalty during the Achaemenid times (555-330 BC). It was, therefore, a highly auspicious occasion for the ancient Iranian peoples. It has been suggested that the famous Persepolis complex, or at least the palace of Apadana and the Hundred Columns Hall, were built for the specific purpose of celebrating Nowruz. Although, there may be no mention of Nowruz in recorded Achaemenid inscriptions (see picture) There is a detailed account by Xenophon of Nowruz celebration taking place in Persepolis and the continuity of this festival in the Achaemenid tradition. According to Britannica, the Jewish festival of Purim, is probably adopted from the Persian New Year. 
Nowruz was the holiday of Arsacid/Parthian dynastic Empires who ruled Iran (248 BC-224 AD). There are specific references to the celebration of Nowruz during the reign ofVologases I (51-78 AD), but these include no details. Before Sassanids established their power in West Asia around 300 AD, Parthians celebrated Nowruz in Autumn and 1st of Farvardin began at the Autumn Equinox. During Parthian dynasty the Spring Festival was Mehragan, a Zoroastrian and Iranian festival celebrated in honor of Mithra.
Extensive records on the celebration of Nowruz appear following the accession of Ardashir I of Persia, the founder of the Sassanid dynasty (224-651 AD). Under the Sassanid Emperors, Nowruz was celebrated as the most important day of the year. Most royal traditions of Nowruz such as royal audiences with the public, cash gifts, and the pardoning of prisoners, were established during the Sassanian era and persisted unchanged until modern times.
Nowruz, along with Sadeh (celebrated in mid-winter), survived in society following the introduction of Islam in 650 AD. Other celebrations such Gahanbar and Mehragan were eventually side-lined or were only followed by the Zoroastrians, who carried them. There are records of the Four Great Caliphs presiding over Nowruz celebrations, and it was adopted as the main royal holiday during the