It refers to the migration of Prophet Muhammad and his followers from Makkah to Madinah in the year 622 CE or the 13th year of Prophethood. This event marks the beginning of the Islamic calendar and is significant in Islamic history as it symbolizes the establishment of the first Muslim community and the escape from persecution. The Hijrah laid the foundation for the development of the early Muslim state, emphasizing principles of cooperation and mutual support, and it is commemorated annually in the Islamic calendar.