SINIC AND HELLENIC UNIVERSAL STATES 661
of physical geography. We have seen that the Han Empire was exposed
at point-blank range to the hlast of Eurasian Nomad explosion along
the enormous length of a Great Wall whose masonry was all that stood
between the nucleus of the Sinic universal state in the Yellow River
Basin and the huge reservoir of Nomad energy in and beyond Gobi.
By contrast, the Roman Empire was nowhere in immediate contact
with the Eurasian Steppe except at the tip of the Steppe's Great
Western Bay where the Iron Gates barred the way farther westward
into the isolated enclave of steppe-land in the Hungarian Alfold.1 Yet
one band of Alan Eurasian Nomads, whose point of departure was this
far-flung western outpost of their native Eurasia, capped their initial
feat of breaking through the Continental European limes of the Roman
Empire by making their way, not only overland into the south-western
extremity of the Continent, but on across the waters of the Western
Mediterranean into the Romans' North-West African island, in the
train of the Vandal war-lord Genseric. And, after thus making their
sea-passage without mishap in A.D. 429, these outlandish invaders from
beyond the extreme opposite sector of the vast Roman perimeter
brought their long trek to a triumphant termination by entering Car-
thage itself within ten years of their audacious landing on African
ground.

This brilliant success of Vandal-led Alan Nomads at the Roman
Empire's expense in North-West Africa in A.D. 429-39 throws into
piquant relief the blackness of the disaster that overtook the Tibetan-led
Hiongnu and Sienpi Nomad assailants of the Sinic World's moated
southern fortress at the very first ditch that these ill-starred barbarian
aggressors tried to cross. The water-jump in the Huai Basin was the
outermost of all the Sinic southern fortress's defences. How was it that
the regulated waterways of a Far Eastern river-basin availed in A.D. 383
to foil the Nomad cavalry who, at the opposite end of the Old World
only forty-six years later, were to commit themselves with impunity to
the less familiar waters of 'the salt estranging sea' when they ventured
to take ship from Europe to Africa in AJD. 429 ?

These versatile Alano-Vandal 'horse-marines' did not merely escape
mishap in making a single sea-passage from Europe to Africa; when
once they had taken to the sea they immediately made themselves so
much at home on this previously unfamiliar element that, from a newly
conquered North-West African base of operations, they succeeded in
wresting back out of Roman hands the naval command of the Western
Mediterranean which the Romans had wrested out of Carthaginian
hands seven hundred years back, in the First Punic War (gerebatur
264-241 B.C.). How was it that the Alano-Vandals were able to master
the sea when the Hunno-Tibetans had been worsted by a river ?

The surprising answer to this irrepressible question seems to be that the
art of marine navigation was less difficult for these centaurs to acquire
than the steeple-chaser's knack of leaping clear from bank to bank
of a fresh-water ditch. The Eurasian Nomad's strange inability to cope
with inland waterways was indeed eventually to prove his undoing

1 See III. iii. 401-2.