the desert dwelling arabs are far worse than the others in their disbelief and hypocrisy and have more reason to be ignorant of the revelations that god revealed to his messenger. god is allknowing and allwise.
الأعراب أشد كفرا ونفاقا وأجدر ألا يعلموا حدود ما أنزل الله على رسوله والله عليم حكيم