The Hijra (‘migration’) marks the foundational moment of the Islamic community as a political entity. After 12 years of preaching in Mecca, facing increasing persecution from the Quraysh (who saw Islam as a threat to their commercial and religious authority over the Ka’ba), Muhammad and his followers migrate ~320 km north to Yathrib (renamed Medina — ‘the city [of the Prophet]’) in 622 AD. The Hijra is the Year One of the Islamic calendar — not Muhammad’s birth, not the first revelation, but this act of community formation. In Medina, Muhammad is not merely a preacher but a political leader and judge. The Constitution of Medina — a compact between the Muslim immigrants (Muhajirun) and the Medinan helpers (Ansar) and the Jewish tribes of Medina — is one of the earliest written constitutional documents in history. The Medinan period produces the bulk of Quranic legislation and ends with Muhammad’s triumphant return to Mecca in 630 AD.