The Abbasid Caliphate differed from others in that it did not have the same borders and extent as Islam. Particularly, in the west of the Caliphate, there were multiple smaller caliphates that existed in relative peace with them.
The major difference between the protist and the animal kingdom is protists are unicellular protozoans and unicellular & multicellular, but animals are multicellular animals.
One of the earliest kingdoms to be divided out were those organisms that lacked a nucleus or organelles in their cells...the prokaryotic organisms. Kingdom Monera was the result, and it contained all the bacteria and related organisms of the prokaryotic type. So now there were three kingdoms.