Parmigiani Fleurier Watch Tonda PF Hijri Perpetual Calender PFH983-1020001-100182. The TONDA PF Hijri Perpetual Calendar is a horological expression of the Tabular Islamic calendar developed by Muslim scholars and astronomers in the 8th century. This system made it possible for historians to convert Islamic dates to Gregorian dates, which in turn has made the Hijri Perpetual Calendar possible. The first year of the Hijri calendar corresponds to the year 622 CE and is marked by the Prophet Muhammad's Hijrah (Arabic for "migration") from Mecca to Medina in what is today Saudi Arabia.