The history of one of the best periods of medieval civilization in the arab world, the apogee of muslim culture. With the passage from the Omayyad dynasty, which had conquered the whole Mediterranean from Spain to Syria including the Middle East, to the one of the Abbasids, the focus of interest returned to Mesopotamia and in particular to Baghdad, while the rest of the immense empire falls under local dynasties. But it is anything but a sign of decline, because what happens in Baghdad and in the neighboring regions between the eighth and the tenth century is, on the cultural, legal, scientific, literary and artistic level, one of the apogees of the Arab and medieval civilization in general. The Arabs in fact promote all the arts and sciences, architecture reaches unparalleled levels and so the miniature. But what matters most is the widening of the cultural horizon: in Baghdad important scholars, scientists and artists of various cultures and religions rush and perform functions. It is the pluralist and universalist declination of Islam itself.