As for Iraq, its breadth, in customary usage, encompasses the breadth of al-Sawad, while its length falls short of that of al-Sawad. Its easternmost point on the Tigris is al-ʿUlth, and on its western side is Ḥarbī. It then extends to the farthest reaches of Basra’s administrative territory at the island of ʿAbbādān. Thus, its length is 125 farsakhs—35 farsakhs less than the length of al-Sawad—while its breadth is 80 farsakhs, like that of al-Sawad. Qudāmah ibn Jaʿfar said: “When squared, this amounts to 10,000 square farsakhs.”

The length of a farsakh is 12,000 cubits according to the ordinary cubit; according to the surveying cubit—which is the Hāshimī cubit—it is 9,000 cubits. Thus, when the latter is multiplied by itself—that is, the area of one farsakh by one farsakh—it amounts to 22,500 jaribs. When this is multiplied by the number of farsakhs, namely 10,000, it amounts to 225,000,000 jaribs.

By estimation, 75,000,000 jaribs are deducted for the sites of hills and mounds; salt flats, thickets, the tracks of roads and highways, river channels, the open spaces of cities and villages, mill sites, post stations, bridges, shādharwāns, threshing floors, places where reeds are laid, brick kilns, and other such features. The remainder of Iraq’s area is therefore 150,000,000 jaribs. Half of it is left fallow, while the other half is cultivated, together with the palm trees, vines, and other trees found throughout it.

If, in addition to what Qudāmah mentioned concerning the area of Iraq, one includes the remainder of al-Sawad extending beyond it—35 farsakhs—the increase over that area is approximately one-quarter of it. This then represents the area of all the land of al-Sawad suitable for cultivation and planting. Yet contingencies and events may render some of it unusable in ways that cannot be quantified.

It has also been said that in the time of Kisra, the area of al-Sawad had reached 150,000,000 jaribs, and that its revenue amounted to 200,087,000 dirhams according to the seven-weight standard, since he levied one dirham and one qafiz—a measure of grain—from every jarib. The area cultivated during ʿUmar’s time ranged from 32,000,000 to 36,000,000 jaribs.

Once the boundaries of al-Sawad and the area of its cultivated lands have been established by what we have mentioned, the discussion turns to its conquest and its legal status.

According to Aḥmad’s position, it was conquered by force. ʿUmar did not divide it among the conquerors; rather, he made it a charitable endowment for all Muslims and left it in the possession of its proprietors, imposing a kharāj upon the land itself. This was to serve as its rent, payable every year, even if it were not—