There are two Islamic (Hijri; or "H") calendars; one is based on the movement of the sun (solar) and noted as "SH"; and the other is based on the movement of the moon; designated "AH". Iran and Afghanistan use the 'SH' calendar while the rest of the Islamic world uses the "AH" calendar. To obtain the Gregorian date (our calendar) from the SH date, simply add 621 or 622. That will produce a 'close enough' date. To obtain the Gregorian date from the AH date, multiply the AH date by 0.97 then add 621 or 622 for a different resulting year.
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