question #3 Sahih al-Bukhari 3930, Book 63, Hadith 155 : How did the loss of tribal leaders in Medina contribute to the spread of Islam in the region?

The day of Bu’ath was a day (i.e. battle) which Allah caused to take place just before the mission of
His Apostle so that when Allah’s Messenger (ﷺ) came to Medina, they (the tribes) had divided (into hostile
groups) and their nobles had been killed; and all that facilitated their conversion to Islam.