After the death of Muhammad, Islam’s founder, in 632 AD, his followers disagreed over a successor (Caliph), thus ‘Sunni’ and ‘Shia’ branches of Islam were established, each later subdivided many times.
Sunnis advocated the leadership of the most qualified (Sunnis are now a strong, but shrinking, Muslim majority). Shiites insisted that the Caliph be the dead leader’s blood relative, as with royalty. Over the centuries until today, much blood has been spilled in conflict between the two groups. Although most Muslim countries contain sizeable numbers of both groups, for much of the past 100 years Saudi Arabia has led the Sunnis while Iran led the Shiites.
The recent collapse of law and order in parts of Syria and Iraq provided opportunities for radical Sunni Islamists to flood in by thousands from neighbouring countries. Mostly financed by rich Sunni Arabs, they arrived from Saudi Arabia, Yemen, other Arab and Gulf states, and places farther away like Bosnia, Chechnya, Pakistan, Afghanistan, and Somalia. Even West European and North American jihadists have come. They hold one common objective – to re-establish the lost dream of a worldwide Islamic shari’a law-ruled nation.