t defence for the same reason. They are indented
by 289 passes capable of being traversed by camels. The mountain border
of Baluchistan contains 75 more, the most important of which focus their
roads upon Kandahar. Hence the importance to British India of Kandahar
and Afghanistan. Across this broken northwest barrier have come almost
all the floods of invasion and immigration that have contributed their
varied elements to the mixed population of India. Tradition, epic and
history tell of Asiatic highlanders ever sweeping down into the warm
valley of the Indus through these passes; Scythians, Aryans, Greeks,
Assyrians, Medes, Persians, Turks, Tartars, and Mongols have all
traveled these rocky roads, to rest in the enervating valleys of the
peninsula.[1221]

[Sidenote: Breadth of mountain barriers.]

Mountains folded into a succession of parallel ranges are greater
obstructions than a single range like the Erz, Black Forest, and
Vosges, or a narrow, compact system like the Western Alps, which can
be crossed by a single pass. Owing to this simple structure the
Western Alps were traversed by four established routes in the days of
the Roman Empire. These were: I. The _Via Aurelia_ between the
Maritime Alps and the sea, where now runs the Cornice Road. II. The
_Mons Matrona_ (Mont Genevre Pass, 6080 feet or 1854 meters
[Transcriber's Note: printer's error incorrectly printed as
kilometers.]) between the headstream of the Dora Riparia and that of
the Durance, which was the best highway for armies. III. The Little
St. Bernard (7075 feet or 2157 meters), from Aosta on the Dora Baltea
over to the Isere and down to Lugdunum (Lyons). IV. The Great St.
Bernard (8109 feet or 2472 meters) route, which led northward from
Aosta over the Pennine Alps to Octodurus at the elbow of the upper
Rhone, where Martigny now stands. Across the broad double rampart of
the Central Alps the Roman used chiefly the Brenner route, which by a
low saddle unites the deep reentrant valleys of the Adige and Inn
rivers, and thus surmounts the barrier by a single pass. However, a
short cut northward over the Chalk Alps by the Fern Pass made closer
connection with Augusta Vindelicorum (Augsburg). The Romans seem to
have been ignorant of the St. Gotthard, which, though high, is the
summit of an unbroken ascent from Lake Maggiore up the valley of the
Ticino on one side, and from Lake Lucerne up the Reuss on the other.

Mountains which spread out on a broad base