Re: When did the state of Palestine exist before the Jews took over their country?
We'll let the mods split this off. But as far I understand from the religo-political situation of the time, any Muslims who sided with Al-Khawarij against the Khalifah and thus the ummah could have been classified as being Khawarij themselves. As enemies of the ummah they would have been treated as Dar-ul-Harb and thus eligible for enslavement (under the aformentioned Islamic rules about it) which would explain the Muslim Berber slave issue.
As a final word on the status of slaves in Muslim history, Muslim nations are the only ones in which slaves have taken over power with very little to no bloodshed on several occasions and across different geographies (the rise of the Mamluks and also the Slave-Kings of Delhi). Such was the historic parity between slaves and freemen.
Again, this parity was eroded over time until you got the mockery that was slavery under the Moroccans and Omanis.
Even if they were kharijitesi, you have to admit, they were put under oppressive governors of the time.
Not all muslim leaders in the past have been saints, sadly we had lost a few to the side of tyranny.