A delegation consisting of the representatives of the twelve important clans of Medina, invited Muhammad as a neutral outsider to Medina to serve as chief arbitrator for the entire community. There was fighting in Yathrib mainly involving its Arab and Jewish inhabitants for around a hundred years before 620. The recurring slaughters and disagreements over the resulting claims, especially after the Battle of Bu'ath in which all clans were involved, made it obvious to them that the tribal conceptions of blood-feud and an eye for an eye were no longer workable unless there was one man with authority to adjudicate in disputed cases. The delegation from Medina pledged themselves and their fellow-citizens to accept Muhammad into their community and physically protect him as one of themselves.
Muhammad instructed his followers to emigrate to Medina until virtually all his followers left Mecca. Being alarmed at the departure of Muslims, according to the tradition, the Meccans plotted to assassinate Muhammad. With the help of Ali, Muhammad fooled the Meccans who were watching him, and secretly slipped away from the town with Abu Bakr. By 622, Muhammad emigrated to Medina, a large agricultural oasis. Those who migrated from Mecca along with Muhammad became known as muhajirun (emigrants).
