in yathrib there were two main tribes, the aws and the khazraj. both were very powerful, they were always at war with one another, and both worshipped idols. also in yathrib were many jews who, unlike the arab at that time, knew that there was only one god, and worshipped him. they had told the arabs many times that a prophet would be coming to them. the time came for the pilgrimage to the ka'bah, and several people from yathrib were going, among them six men from the tribe of khazraj. they had heard about the prophet mohammed's preaching and thought that must be the prophet the jews had told them about. so they decided to go speak to him during their stay in mecca. they met the prophet (pbuh) at a spot known as 'aqabah, near mecca, and he invited them to sit with him. he explained to them what islam meant and recited to them from the koran. when they heard the koran recited it touched their hearts so deeply that they became muslims and on leaving mecca they promised to return the following year. when they reached yathrib carrying islam in their hearts, they told their relatives and friends what they had heard from the prophet (pbuh) and many more people became muslims.
a year passed and the pilgrimage season came around again.

twelve important men from yathrib went to mecca to meet the prophet (pbuh) and promised faithfully to serve him and islam. in return, the prophet (pbuh) sent one of his friends, mus'ab ibn 'umayr, with them to teach the koran and instruct them in their new religion. another year passed and still more muslims came from yathrib to mecca for the pilgrimage. on this occasion a secret meeting with the prophet (pbuh) was arranged to be held at night. seventy-three men and one woman from yathrib came, and the prophet (pbuh) arrived with his uncle, al-'abbas. during this meeting the men from yathrib offered to protect and defend the prophet (pbuh) and his followers if they would come to live in yathrib. this promise of protection came to be known as the treaty of 'aqabah.

the treaty was most fortunate for even though islam was growing in yathrib, the muslims in mecca were still suffering. the prophet (pbuh) therefore told his friends and followers to go to yathrib where they would be safe,

and most of them took this opportunity to leave. despite all this suffering the prophet (pbuh) was not allowed to fight his enemies, for allah had told him to forgive those who insulted him or would not listen to his message. but the quraysh had closed their minds so utterly to the word of allah, and grew so hard-hearted towards the prophet (pbuh)and his followers, that allah gave permission to the prophet (pbuh) to fight those who tried to harm him or his companions.
in the name of allah, the beneficent, the merciful
"permission is given unto those who fight because they have been wronged; and allah is surely able to give them victory; those who have been driven from their homes unjustly only because they said: our lord is allah".(koran xxii.39-40)
quraysh began to fear the prophet (pbuh) for they realised that he was now strong enough to fight them and had been given leave to do so by allah. they also knew that he now had the people of yathrib to help and protect him.

seeing that the muslims were leaving the city, they decided to kill the prophet (pbuh), before he, too, left mecca to join his followers in yathrib. in this way they hoped to put an end to islam once and for all.