With the revelation of God the Creator as the benevolent almighty judge, a revelation given in the Arabic language, he founded Arab monotheism – a world view, a code of values and a social order – and the Arab nation. Above the solidarity of individual tribes he placed the solidarity of the community (umma) which was sanctioned by the duty of every individual towards God, and thus gave new direction to a society in transition.
It was the revelation of the Medinan period above all (after the Hijra, emigration, of 622) that laid the foundation of the legal and governmental system of the empire which was to come. With the subjugation of the Arab tribes in the last years of his life Mu˙ammad created the military and – by converting the community to faith in Islam – the spiritual basis of an expansion which was to begin after his death.In the first century after the death of Mu˙ammad the tribes of Arabia, having converted to Islam, conquered an empire from the Atlantic to the Indus. The institutions of the Islamic state were established and formulated; through the medium of the Arabic literary language the Muslims created the foundations of classical Islamic culture.