The present volume of al-Tabari's monumental history covers the years 255-265/869-878, the first half of the reign of the Abbasid caliph al-Mu'tamid in Samarra. Although the decade was one of relative calm in the capital, compared with the anarchy of the years immediately preceding, danger signals were flashing in territories adjacent to the imperial heartlands. Chief among them was the revolt of the Zanj, the narrative of which occupies the bulk of the present volume.