INTRODUCTION 41 construction in Nishapur. In this period there were several insurrections against the caliphate and many changes of governor. That Nishapur was an important place at this time is obvious from the number of times it is men­ tioned by contemporary writers and from the fact that two caliphs, before succeeding to that high office, were honorary governors there: al-Mahdi in 758 and al-Ma'mun in 796. The latter lived in Nishapur six years before he was installed at Baghdad. During the caliphate of his father, Harun al-Rashid (r. 786-809), we hear of his being given by Ali ibn Isa, governor of Khurasan from 796 to 8o6, a magnificent gift of Chinese porcelain. This is a matter of some interest in regard to the pottery of Nishapur in that the remains of Chinese porcelain and pottery were found in the Museum's excavations. After playing its part in the rise to power of the Abbasid dynasty, Khurasan became, in the ninth century, a virtually autonomous province. The beginning of this development can be said to be Caliph al-Ma'mun's appointment, in 82o, of a new governor for the eastern region. This ruler, Tahir ibn al-Husain, an able and successful general, nicknamed Ambidexter, had his capital at Merv. The dynasty that he established, and that flourished mostly within the bounds of Khurasan, is known as the Tahirid. As far as Nishapur is concerned, the most important of the Tahirids was 'Abdallah (r. 828-45), the second of the line, who chose Nishapur as his capital, deeming its climate better and its larger population generally more agreeable than those of Merv. 'Abdallah ibn Tahir built his palace and his officers' quarters in the most famous of the suburbs of Nishapur, Shadyakh, approximately 5 kilometers from the city proper. The name presents some difficulties: first because it is sometimes identified with Nishapur itself, and second because it has not always been ascribed to precisely the same place. In the twentieth century the name has been associated with an area enclosed by high ruined walls to the west of the shrine of Muhammad Mahruq and the tomb that is assumed to be that of Omar Khayyam; this is where Shadyakh is indicated on Sykes's map ("Sixth Journey in Persia," p. 153). There is reason, as will be seen later, to believe that the original Shadyakh lay to the east of this walled enclosure. That Nishapur was vastly improved as a city under 'Abdallah ibn Tahir is suggested by the fact that he spent a million dirhems of his own fortune in building qanats (Bosworth, Ghaznavids, p. 157). The Tahirid dynasty, after about fifty years, was displaced by the Saffarid, which, like its predecessor, was more or less autonomous, operating sometimes with and sometimes without the caliph's approval. Military adventurers, the Saffarids came to power under Ya'qub ibn Layth al-Saffar (the Coppersmith), who expanded his sphere of influence from the province of Sistan, south of Khurasan, to .