Nothing is more disconcerting to the student of early Muslim history than the way in which Tabarī and the other historians alternate between detailed and comprehensive narrative and jottings of the most meagre and involved nature, filled out, in some cases, by picturesque but obviously legendary tales. These faults, which are to a large degree inherent in the method of compilation from oral tradition, come out most clearly in the narrative of the brilliant series of campaigns by which the Arab general Qutayba ibn Muslim conquered and annexed the lands eastward from Herāt and the Oxus to the Pamīr, during the reign of the Umayyad Caliph Walīd I (a.d. 705–15). Thus we are given a fairly sufficient account of the long drawn out operations against Bukhārā, but none of the actual conquest and colonization of the city : much 'of the expeditions against various princes subject to the kingdom of Tukhāristān, but practically nothing of the annexation of Tukhāristān itself.