Prophet Muhammad (pbuh) decided to leave Mecca because the Meccan chiefs had taken action to kill him at his home. It was the year 622 CE. As far the choice of migrating to Medina (known as Yathrib at that time), the decision was made easier by the second ‘Pledge of Aqaba’ made a year before on the occasion of the annual rites of pilgrimage. The pledge was made by seventy three men and two women of Khazraj and Aws communities of Medina. They had accepted Islam and wanted to invite the Prophet to migrate to Medina. Their motivation for this move, apart from recognizing him as the Prophet, the trustworthy, and the best in conduct in Mecca, was to bring peace and security between the Khazraj and Aws. They were often at war with each other and the Battle of Bu'ath had shattered their strength completely. They desperately needed a leader who could be trusted by both communities and bring peace in Medina. As part of the pledge, they were to protect the Prophet as they would protect their women and children if he were attacked by the Meccans.

Among the people in Medina, there was a small community (three tribes) of Jews with Arab communities constituting the majority of the population. Because of wars going on for several generations, the resources of the Arabs were depleted and their influence in Medina was dwindling. The Jews were traders and many of them used to lend money at exorbitant interest. The continuing wars boosted their economy and personal wealth.

The immediate result of the Prophet’s migration to Medina was peace and unity between the communities of Aws and Khazraj. The Prophet, motivated by the general welfare of citizens of Medina, decided to offer his services to the remaining communities including the Jews. He had already laid down the basis for relationship between the Emigrants from Mecca (known as Muhajirin) and Medinites (known as the Ansar, the helpers).

The Treaty between Muslims, non-Muslim Arabs and Jews of Medina was put in writing and ratified by all parties. It has been preserved by the historians. The document referred Muhammad (pbuh) as the Prophet and Messenger of God but it was understood that the Jews did not have to recognize him as such for their own religious reasons. The major parts of the document were:

“In the name of Allah (The One True God) the Compassionate, the Merciful. This is a document from Muhammad, the Prophet, governing the relation between the Believers from among the Qurayshites (i.e., Emigrants from Mecca) and Yathribites (i.e., the residents of Medina) and those who followed them and joined them and strived with them. They form one and the same community as against the rest of men.

“No Believer shall oppose the client of another Believer. Whosoever is rebellious, or seeks to spread injustice, enmity or sedition among the Believers, the hand of every man shall be against him, even if he be a son of one of them. A Believer shall not kill a Believer in retaliation of an unbeliever, nor shall he help an unbeliever against a Believer.

“Whosoever among the Jews follows us shall have help and equality; they shall not be injured nor shall any enemy be aided against them.... No separate peace will be made when the Believers are fighting in the way of Allah.... The Believers shall avenge the blood of one another shed in the way of Allah ....Whosoever kills a Believer wrongfully shall be liable to retaliation; all the Believers shall be against him as one man and they are bound to take action against him.

“The Jews shall contribute (to the cost of war) with the Believers so long as they are at war with a common enemy. The Jews of Banu Najjar, Banu al-Harith, Banu Sa'idah, Banu Jusham, Banu al-Aws, Banu Tha'labah, Jafnah, and Banu al-Shutaybah enjoy the same rights and priviledges as the Jews of Banu Aws.

“The Jews shall maintain their own religion and the Muslims theirs. Loyalty is a protection against treachery. The close friends of Jews are as themselves. None of them shall go out on a military expedition except with the permission of Muhammad, but he shall not be prevented from taking revenge for a wound.

“The Jews shall be responsible for their expenses and the Believers for theirs. Each, if attacked, shall come to the assistance of the other.

“The valley of Yathrib (Medina) shall be sacred and inviolable for all that join this Treaty. Strangers, under protection, shall be treated on the same ground as their protectors; but no stranger shall be taken under protection except with consent of his tribe....No woman shall be taken under protection without the consent of her family.

Whatever difference or dispute between the parties to this covenant remains unsolved shall be referred to Allah and to Muhammad, the Messenger of Allah. Allah is the Guarantor of the piety and goodness that is embodied in this covenant. Neither the Quraysh nor their allies shall be given any protection.

“The contracting parties are bound to help one another against any attack on Yathrib. If they are called to cease hostilities and to enter into peace, they shall be bound to do so in the interest of peace; and if they make a similar demand on Muslims it must be carried out except when the war is agianst their religion.

“Allah approves the truth and goodwill of this covenant. This treaty shall not protect the unjust or the criminal. Whoever goes out to fight as well as whoever stays at home shall be safe and secure in this city unless he has perpetrated an injustice or commited a crime.... Allah is the protector of the good and God-fearing people.”

The first written constitution of a State ever promulgated by a sovereign in human history emanated from the Prophet of Islam. It was enacted from the first year of Hijrah (622 CE). The treaty stipulated a city state in Medina, allowing wide autonomy to communities. Private justice was to be banished. The head of the State had the prerogative to decide who should participate in an expedition, the war and peace being indivisible. Social insurance was to be instituted.

The name Yathrib was changed to Medinat-un-Nabawi, meaning the 'City of the Prophet' soon after he migrated there. The use of only the first word in that name (i.e., Medinah) became popular later.

History does not record much as to when first Jewish migration from north to Yathrib (Medina) began as their numbers remined small throughout their stay there. Among the major reasons for their settlements in Arabia were: the relative peace and security in north Arabia with orchards and gardens; the Arab trade route linking Yemen, Arabia, Syria and Iraq; and continuing tensions resulting from wars between the Romans and Persians in the area around the Holy Land. Some of the learned men among the Christians and Jews had also moved to this area based on their conviction that the advent of the final Prophet of God was near, who was to settle in this area. Bahira, the monk, and Salman, the Persian, were some of the people who moved to the caravan route to or near this area. Salman was told by his last Christian sage:

“He will be sent with the religion of Abraham and will come forth in Arabia where he will emigrate from his home to a place between two lava tracts, a country of palms. His Signs are manifest: he will eat of a gift but not if it is given as alms, and between his shoulders is the seal of prophesy.”

Yathrib was the only city fitting this description.

Salman (ra) was born into a Zoroastrian family of Isfahan, Persia. He became a Christian as a young boy and traveled to Syria in search of truth about God and associated himself with the Bishop of Mosul and after the Bishop's death to several other Christian sages. On one of his travels to Gulf of 'Aqaba, north of Red Sea, he was sold to a Jew as a slave by his caravan leader. Salman (ra) was then sold again to a Jew of Banu Quraizah in Yathrib just before Prophet Muhammad’s migration.

After confirming these signs, Salamn (ra) accepted Islam and, due to his sincerity and dedication to Islam, he was accepted by the Prophet as ‘one of the Prophet’s household.’ It was on his advice a trench was dug around Medina. The trench (in the 'Battle of Ahzab,' also known as the 'Battle of Trench') took the Meccan army by surprise and they and their confederates (Arabs and Jews) could not accomplish the plan of wiping out Islam and Muslims of Medina.