Complex sentence: Since the sixteenth century AD Iran has been the only country in the world having Shi’ah Islam as its official religion, consequently the general principles of its legal system differed somewhat from those of other countries which followed Islamic law.
Split into simpler sentences: Since the sixteenth century AD Iran has been the only country in the world having Shi’ah Islam as its official religion. This is why the general principles of its legal system are somewhat different from those found in the other countries having officially adopted Islamic law.