Islam began in the 600s AD when the angel Gabriel revealed the Quran to Muhammad near Mecca. Muslims believe Allah put the words of the Quran into Muhammad's head. Muhammad began preaching in Mecca, causing tension as it was a polytheistic city, forcing him to leave. By 624 AD, Muhammad slowly built an army and conquered Mecca by 629 AD, destroying all religious idols. After Muhammad's death, a power struggle emerged between Abu Bakr and Ali Talib over who would lead the Muslim community, dividing Islam into the Sunni and Shia sects that still exist today with ongoing geo-political issues.