What Event Marks Year One According To The Muslim Calendar. 622 to establish the first muslim. One year consists of twelve months, of which four are sanctified months, three of them are in sequence;

The islamic calendar was introduced by hazrat umar bin al khattab, the second caliph of islam and one of the closest companions of our prophet muhammad. The event occurs on the first day of muḥarram, which is the first month in the calendar.