Parsi New Year is a regional holiday celebrated on August 17th in India. It is also known as Jamshedi Navroz after the legendary King of Persia, Jamshed who started the Parsi Calendar and Navroz meaning new day. Parsis follow the religion of Zoroastrianism, one of the oldest known monotheistic religions. It was founded by the Prophet Zarathustra in ancient Iran approximately 3,500 years ago. It was one of the ancient worlds most important religions for over 1000 years and was the official religion of Persia (now Iran) from 650 BCE until the rise of Islam in the 7th century.
When the Islamic armies invaded Persia, many Zoroastrians migrated, to places such as Gujarat in India and Pakistan. Nowadays there are an estimated 2.6 million Zoroastrians worldwide, with the Parsis (Parsi being Gujarati for Persian) in India being the largest single group. In Iran and other parts of the Middle East, Zoroastrians celebrated the Persian New Year using the Fasli/Bastnai calendar, which fixed the first day of the year on the Spring Equinox, usually March 21st. To this day, this remains a popular festival, known as Nowruz, celebrated by many peoples and cultures in the region, despite not being Zoroastrians.
The Parsis however, observe the new year using the Shahenshahi calendar which does not account for leap years, meaning this holiday has now moved by 200 days from its original day of the vernal equinox. Parsi New Year is celebrated in much the same way as Nowruz, with a focus on celebrating the renewal that a new year brings such as house cleaning, wearing new clothes, giving gifts and making charitable donations.