How did the leaders of Medina embrace Islam at the time of the prophet?

In a Nutshell: Musab (ra) visited the people of Medina in their tribal communities and worked on the conversion of both leaders and individuals. The most important in his dawa was his call to two leaders of Medina who accepted the call and the whole Medinan society then followed them in their decision. Leaders of Medina embrace Islam  The Prophet (saw) sent Mus'ab ibn Umayr (ra) to pave the way before the migration of the Prophet (saw) and his companions (ra).  As'ad ibn Zurarah assisted the companion Mus'ab ibn 'Umayr in his activism whilst he was in Medina. He accompanied him to the areas of various tribes including Banu al-Ashhal and of Banu Zafar. They entered one of the gardens of Banu Zafar by a well and sat in it, where some of the men who had accepted Islam had gathered together. Sa'd ibn Mu'adh and Usayd ibn Hudayr were at the time leaders of their clan, the Banu 'Abd al-Ashhal, and both followed the polytheism of their tribe. When they had heard about Musab, Sa'd said to Usayd, "Go to these fellows who have entered our quarters to make fools of our comrades, drive them out and forbid them from entering our quarters. If it were not that As'ad ibn Zurarah is related to me I would save you the trouble. He is my aunt's son and I can do nothing to him." Ibn Hisham narrated: فَلَمَّا سَمِعَا بِهِ قَالَ سَعْدُ بْنُ مُعَاذٍ لِأُسَيْدِ بْنِ حُضَيْرٍ: لَا أَبَا لَكَ، انْطَلِقْ إلَى هَذَيْنِ الرَّجُلَيْنِ اللَّذَيْنِ قَدْ أَتَيَا دَارَيْنَا لِيُسَفِّهَا ضُعَفَاءَنَا، فَازْجُرْهُمَا وَانْهَهُمَا عَنْ أَنْ يَأْتِيَا دَارَيْنَا  "When they heard of Musab, Saad ibn Mu'adh told Usayd ibn Huddayr, 'What is wrong with you, go to these two men (Musab and Asaad ibn Zurara) who had come to our society to mislead our powerless people; discourage and prevent them from coming to hour homes again.'" (Ibn Hisham, as-Seera al-Nabawiyah, Vol. 1, pp. 438) So Usayd took his lance and went to them; when As'ad saw him he said to Mus'ab, "This is the chief of his tribe who is coming to you, so be true to Allah with him." Mus'ab said, "If he will sit down, I will talk to him." He stood over them looking furious and asking what they meant by coming to deceive their weaker comrades. "Leave us if you value your lives." Musab replied, "Won't you sit down and listen. If you like what you hear you can accept it, and if you don't like it you can leave it alone." Usayd agreed that was a fair request, stuck his lance in the ground, and sat down. Musab explained Islam to him and read the Qur'an to him. Usayd commented, "What a wonderful and beautiful discourse this is! What does one do if he wants to enter this Deen?" They told him that he must wash and purify himself and his garments, then bear witness to the Truth and pray two Rak'at. He immediately did so and said, "There is a man behind me who if he follows you every one of his people will follow suit. I will send him to you at once. It is Sa'd ibn Mu'adh." Taking his lance, he went off to Sa'd and his people sitting in a meeting place. When Sa'd saw him coming, he said, "By Allah, Usayd is coming with a different expression from that which he had when he left you." And when he came up he asked what had happened, he said, "I have spoken to the two men and I find no harm in them. I forbade them to go on and they said to me: We will do what you like, and I was told that Banu Harithah had gone out against As'ad to kill him because they knew that he was the son of your aunt so as to make you appear a treacherous protector of your guests." Sa'd was enraged and got up at once, alarmed at what had been said about the Banu Harithah. He took the lance from his hand saying, "By Allah, I see that you have been utterly ineffective." He went out to them and when he saw them sitting comfortably he knew that Usayd had intended that he should listen to them. He stood over them, looking furious. He said to As'ad, "O Abu Umamah, were it not for the relationship between us you would not have treated me thus. Would you behave in our homelands in a way we detest?" As'ad already had said to Mus'ab, "O Musab, by Allah the leader who is followed by his people has come to you. If he follows you, no two of them will remain behind." So Musab said to him, "Won't you sit down and listen. If you like what you hear you can accept it, and if you don't like it you can leave it alone." He agreed that was fair, stuck his lance in the ground, and sat down. He explained Islam to him and read for him the Qur'an. He said, "What a wonderful and beautiful discourse this is! What does one do if he wants to enter this Deen?" They told him that he must wash and purify himself and his garments, then bear witness to the truth and pray. He immediately did so. Then he took his lance and went back to his people's meeting place accompanied by Usayd ibn Hudayr. When they saw him coming they said, "We swear by Allah, Sa'd has returned with a different expression from that which he had when he left you."  And when he stopped by them he said, "O Banu 'Abd al-Ashhal, how do you rate my authority amongst you?" They replied, "You are our chief, the most active in our interests, the best in judgment and the most fortunate in leadership." He said, "I will not speak to a man or woman among you until you believe in Allah and his Messenger." As a result, every man and woman among the Banu 'Abd al-Ashhal embraced Islam. Musab then returned to the house of As'ad ibn Zurarah and he stayed with him as a guest. He continued to call the people to Islam until almost every household of the Ansar had Muslim men and women among them. Musab ibn Umayr remained in Madinah for one year among the Aus and the Khazraj teaching them the Deen.    Conclusion Musab (ra) visited the people of Medina in their tribal communities and worked on the conversion of both leaders and individuals. The most important in his dawa was his call to two leaders who the whole society converted after their conversion. Musab's dawa used to including knocking on people's doors, walking to the fields and calling the farmers to Islam. He also used to meet the leaders and call them to the deen of Allah, performing deliberate tactics to gain access to influentials. He managed in one year to turn the thoughts and emotions of Medina to Tawheed and iman and Islamic emotions and away from acts such as shirk, cheating, fraud and other vices. As a result of his activities and activities of those who embraced Islam, Medina in one single year transformed from a people who committed shirk to people who turned to Islam.