The Hijri year (Arabic: سَنة هِجْريّة‎) or era (التقويم الهجري at-taqwīm al-hijrī) is the era used in the Islamic lunar calendar, which begins its count from the Islamic New Year in 622 AD. During that year, Muhammad and his followers migrated from Mecca to Yathrib (now Medina). This event, known as the Hijra, is commemorated in Islam for its role in the founding of the first Muslim community (ummah).