This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Islam is established as a political community at Medina in 622, when Muhammad and his followers emigrated there from Mecca. The emigration itself, the Hijra, is remembered as foundational enough that it marks year one of the Islamic calendar, the point this atlas records as the end of Islam's Mecca period and the beginning of something structurally new.
Muhammad carried the transition himself, and what he did once he arrived at Medina went well beyond finding refuge there. He drew up a constitution establishing relations among the Muslims, the Jewish tribes and the other Medinans under his own arbitration, a document that gave the community its first standing as a political and legal body with its own recognized authority, rather than only a religious movement gathered around a preacher.
What changed for Islam's spread is the community's own capacity to act as more than a persecuted minority. With a defined territory, a governing arrangement and Muhammad's own arbitration at its center, Medina gave the new faith the institutional footing from which the campaigns that would carry it into Syria, Egypt and Persia within a generation could be organized and launched. Where Mecca had been the place the message first took shape, Medina is recorded here as the point Islam became a functioning polity in its own right.