Al-A`rab signifies the bedouin - whether of the desert or the countryside - in the vicinity of Madina. For a long time they had followed a policy of opportunism with regard to the conflict between Islam and unbelief. However, as Islam established its sway over the greater part of Hijaz and Najd and the power of the tribes hostile to Islam began to weaken, they saw their interests lay in entering the fold of Islam. For details see Surah 9.