Complex sentence: It is for these reasons Qays ʿAylān confederation were eager to join any revolution against the Caliphate, which occurred with the confederation taking up arms in revolt opposing the Caliphate, along side the Qarmatians and later on the Fatimids.
Split into simpler sentences: It is for these reasons the Qays ʿAylān confederation were eager to join any revolution against the Caliphate. This did occur with the confederation taking up arms in revolt along side the Qarmatians, and later on the Fatimids.