ADMINISTRATIONdynamic rather than static and to distinguish and compare different
kinds of responsibilities and officials. For the purposes of comparison,
the nature of an administrative jurisdiction is as important as its ex-
istence.
The administrative division of Sasanian Mesopotamia into the three
provinces of Arbayestan, Adiabene, and Asoristan lasted through the
fifth century.2 Then, in the sixth century they were combined in a
larger unit called the Quarter of the West (Khvarvaran), following the
administrative reforms carried out under Khusraw Aniishirvan which
divided the Sasanian state into four quarters oriented to the points of
the compass.^3 The late Sasanian Quarter of the West included as much
of the Tigris-Euphrates valley above Maysan as was under Persian
control, plus western Media Uabal). In the time of Khusraw Parviz,
a military governor (N.P. spahbadh or ispahbadh), a lieutenant gov-
ernor (N.P. piidhghOspiin), and possibly a finance official were in
charge of the Quarter of the West. Part of the difficulty in determining
how much of the organization of this larger unit was preserved under
Muslim rule lies in the existence of two layers in the system, one
imposed on the other, in the late Sasanian period. The first layer had
been produced at the time of the quartering of the empire in the sixth
century and involved the creation or reorganization of the districts
called kuwar (Gk., sg. kura) and their subdivisions called tasiistj (M.P.,
sg. tassuj), which began under Qubadh 1,4 Khusraw Parviz is then said
to have reorganized the entire empire into some thirty-five adminis-
trative districts in the early seventh century.s At that time the old
subdivisions of the Quarter of the West were apparently collected into
six or seven main divisions within the new system: one around Nasibin;
one north and east of the upper Tigris; one east of the middle Tigris;
one between the middle Tigris and the middle Euphrates; one between
the lower Tigris and the lower Euphrates; and a frontier district south-
west of the middle Euphrates around Hira (see fig. 5).
Two schematic descriptions of the late Sasanian provincial system
lead to this conclusion. Although neither of them is entirely consistent
or reliable, or possibly even complete, they seem to have been based
on official lists and provide a useful starting point. The older of the
two lists appears in the Armenian Geography (Ashxarhac'oyj and
belongs to the period between 591 and the reorganization by Khusraw
2 L. Dillemann, Haute Mesopotamie orientale et pays adjacents (Paris, 1962), p. 114.
3 Dinawari, Akhbiir at-pwiil, p. 69; Tha'aJihi, Ghurar, p. 609.
4 Dinawari, Akhbiir at-pwiil, p. 68; Ya'qiibi, Ta'rikh, I, 186.
5 Christensen, Sassanides, p. 40.