'IRAQ AND THE PERSIAN GULF' [‎63v] (131/862)

8o
GEOLOGY AND DESCRIPTION OF THE LAND
westwards along the southern foot of the Jabal Mak-hul to the Wadi A seasonal or intermittent watercourse, or the valley in which it flows.
Tharthar, a deflection that led to the founding of the desert caravan
city of Hatra in Parthian times. In its neighbourhood there have
always been water and plentiful grazing for camels, and in ancient
times the caravan trade needed protection from desert raids. It was the
dues levied on such traffic that brought wealth to Hatra on the trade-
route between Nisibis and the Tigris (p. 234).
From Qala Sharqat to Qaiyara the plain west of the Tigris is open,
though cut deeply by the Wadi A seasonal or intermittent watercourse, or the valley in which it flows. Jirnaf and its tributaries, especially
near the Tigris. North of Qaiyara is an important line of low hills
stretching north-westwards to Tel Afar, where a break affords easy
communication between Mosul and Balad Sinjar. Between this line
of low hills—the Jabal Qaiyara (or J. Najma), J. Jawan, J. Umm al
Shanin, and J. Shaikh Ibrahim, none of which rise more than 500-700
feet above the plain—and the Tigris at Eski Mosul, the surface of
the plain is much broken by ravines and low limestone ridges. The
easiest ground is now, as it was in ancient times, along the open plain
by the south-west foot of this line of hills, since farther west the
desert again becomes cut up by the tributaries of the Tharthar. West
of Tel Afar the hills change direction to due west and form the Jabal
Sasan (1,962 ft.) and Jabal Sinjar (photos. 22, 23). This range rises
to 4,781 feet at the highest summit, and is continued into the Syrian
Jazira by the lower Jebel Jeribeh. Much of it is inhabited by
Yezidis (p. 330), and there is a fairly broad belt of rain-fed culti
vation on the plain south of it. Balad Sinjar, the chief town, lies close
under the southern flank; it marks the site of the walled Roman for
tress of Singara (p. 236), and the Roman defended frontier {Limes)
passed along the southern foot of the Jabal Sinjar through Singara to
Zagurae (near Tel Afar) and the Tigris at Eski Mosul near the junction
of the perennial Wadi A seasonal or intermittent watercourse, or the valley in which it flows. al Murr. It was along the general direction of
this stream that the ancient caravan route ran to Nisibis, to be
followed later by the Turkish military road and to-day by the modern
standard-gauge railway that links Baghdad with Aleppo and the
Bosporus opposite Istanbul. Eski Mosul (‘Old Mosul’) marks the
site of an important walled town in the past, subsequent to Nineveh
but before the building of Sassanid Mosul. The whole Sinjar
region formed a defensive zone with a close network of roads and
forts {castella), designed to prevent Parthian and Sassanid irruptions
into Roman Syria through the well-watered region of the northern
Jazira and Turkish foothills. Hatra, though close to the Roman
frontier, withstood successfully several assaults and sieges by Romans