"كتيّب الجزيرة العربية. المجلد I. ١٩١٧" [‎١‎٣] (٧٤٨/٢٢)

PHYSICAL FEATURES
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mitted a passage from the Euphratean lowlands (Nejef and Samawah)
to Nejd, which, on several lines, has been utilized by the Shiah
pilgrimage since the early days of Islam.
On the east, dahandh, merging into steppe or nefud on its flanks,
broadens from the neck just mentioned, and runs SE. in a con
tinuous belt. On or about the Tropic, east of Oman, it joins the
enormous block of the south desert— and in the
east and ahqdf in the west—which lies all across the butt-end of the
peninsula.
This south desert, which at its eastern and lower end begins
below the westward slopes of the Oman mountain system and
touches the south-eastern shore-line itself for a considerable distance,
is so broad throughout (400 to 500 miles) that it absolutely bars
passage from the southern coastal districts to the centre. Arab
writers call it' The Abode of Emptiness ' (Ruba' el-Khali), and the
vulgar tongue terms it Er-Raml, ' The Sand' It is
not certainly known ever to have been crossed, on any central line,
by human foot.
On the west the ring is broken by a steppe-interval of about 400
miles between the north-western corner of the great south desert
and the southernmost Inarrah tracts, which occur thereafter in a series
till they meet the Nefud N. of Teima. This interval is ill known ;
but it is certain that, except for short distances along the lines of
rare wadi-depressions which run inland north-eastward from the
western watershed, it is filled with, at best, very lean steppe-tracts,
averaging over 200 miles from west to east. Though not easy of
passage except by nomads or well-provided parties and caravans,
the avenues through this gap to the centre of the peninsula are
the least difficult, on the whole, of any routes to the interior;
and the gap, coinciding with a depression in the western moun
tain system, explains the social importance of Mecca and Medina in
all ages.
Central Oases. —Within this inner ring of desert and steppe
lies an elevated core of discontinuous fertility, which may be dis
tinguished into three groups of more or less connected oases :—
1, Jebel Shammar, 2, Qasim, and 3, Nejd (proper).
1. Jebel Shammar, south of the northern Nefud, owes its settled
population to the drainage from two lofty ranges called
Aja and Jehel Selmah, which run from SW. to NE. The Nefud,
however, throws out southward tongues round the butts of the
ranges, virtually enveloping the hill-system. The large town of
Ha'il, therefore, which, with an older town, Feid, and a score of
villages, large and small, occupies the neighbourhood of the two