[Albion Wilde]

Isn’t each “caliph” supposed to be a lineal descendent of Mohammed?

Apparently that fight is what defines the split between the sunni and the shia muslims that has figured into the various wars in Iraq. The shia (10 - 13% minority) believe so. The sunni (87 - 90% majority) believe not. The ISIS forces are sunni.

OK, it's by Couric; but here's a condensed explanation on video that should have been published ten years ago:

Now I Get It: Sunni vs. Shia Muslims in Iraq

[pfony1]

Thank you!