Ibn Ishaq writes: Only one side of Madinah was exposed, and the rest of the sides were strongly protected by buildings and date-palm groves through which an enemy could not get access.
The Prophet (peace be upon him) had perhaps covertly referred to this very aspect of Madinah when he said before his migration: I have been shown the goal of your migration – a land of palm-trees lying between two tracts strewn with black, rugged stones. All those who resolved upon migration proceeded thereupon to Madina. (Bukhari, chap. Migration).
The two Arab tribes of Madina, the Aus and the Khazraj, were well known for their passionate, chauvinistic spirit of the clan; self-respect, boldness and valor while riding horses was one of the manly skills in which they excelled. Freedom of the desert was in their blood: neither had they ever submitted to any authority nor paid impost to a sovereign. The heroic character of these tribes was plainly set forth when the chief of Aus, Sad Ibn Muadh had said to the Prophet (peace be upon him) during the battle of Trenches: When we and these people were polytheist and idolaters, not serving God nor knowing Him, they never hoped to eat a single date except as guests or by a purchase. (Ibn Hisham, Vol. II, p. 289)
The two clans of Yathrib… writes Ibn Khaldun, …dominated over the Jews and were distinguished because of their prestige and eminence. The tribe of Mudar, which was just around the vicinity, was cognate with them. (Tarikh Ibn Khaldun, Vol. II, p. 289) Ibn Abd-I-Rabbehi, another Arab historian, writes in the Al-Iqd al-Farid; The Ansaar descended from the tribe of Azd. Known as Aus and Khazraj, they were lineal descendants of the two sons of Haritha Ibn Amr Ibn Amir. Being more proud and dignified than others, they had never paid tribute to any regime or supremacy. (Al-Iqd ul-Farid, Vol. III, p. 334)
They were related, on the material side, to the Banu Adiy Ibn al-Najjar who had given one of their daughters, Salma bint Amr, to Hashim in marriage. To Hashim she bore Abdul Muttalib, but Hashim, however, left the boy with his mother in Yathrib where he was brought up and was taken to Mecca by his uncle after he had grown up into a youth. These blood relationships, which were the adhesive elements in tribal organization, cannot be ignored since kinship played an important role in the social life of the Arabs. On reaching Madinah, the Prophet (peace be upon him) stayed with Abu Ayyub Ansari who belonged to Banu Adiy Ibn al-Najjar.
Aus and Khazraj traced back their roots from Qahtan while Muhajirrin and other Muslims hailing from Mecca or other places close to it claimed their descent from Adnan. Thus, after the Prophet (peace be upon him) migrated to Madinah and the Ansaar pledged their support to him, both the Adnan and Qahtan had been at odds with one another during the pre-Islamic times but they were banded together in Madinah and thus the pagan passions of blood and clan, of vanity and pride and of contemptuous self-conceit were abolished by the wholesome influence of Islam.
For all these causes and considerations as well as for its strategic location, Madinah was the fittest place to be selected for the emigration of the Prophet (peace be upon him) and his companions as it was eminently suited to be made the radiating center of Islam until it gained enough strength to prevail over the Peninsula and charged the whole country with a new spirit of virtue and godliness.
EXPANSION OF ISLAM IN MADINAH
The teachings of Islam were so contagious that the people of the Aus and the Khazraj, awakened to interest, quickly attested their faith in it. Sad Ibn Muadh was the first to embrace, then Usayd Ibn Hudayr, the leader of Bani Abdul Ashhal, a clan of Aus followed suit. The wise and courteous stance of Musab Ibn Umary, together with the proper manner in which he presented Islam to them, convinced these people of the truth that is Islam. Then the remaining clansmen of Bani Abdul Ashal were led to accept the faith such that shortly thereafter, there was not a house of the Ansaar in which a man or a woman had not given his or her faith to Islam. (Ibn Hisham, Vol. I, pp. 436-38)