There is another light in which this vast desert may be looked at. Unquestionably, its influence on the destinies of the human race has been injurious; it has checked the progress of the Semitic civilization. The primitive peoples of India and Tibet were civilized at an early period of the world's history; but the immense wilderness put an impassable barrier between them and the barbarous tribes of Northern Asia. More than the Himalaya, more than the snow-capped peaks of Sirinagur and Gorkha, these boundless wastes, alternately withered by a tropical summer, and blighted by a rigorous winter, have prevented for ages all intercommunication, all fusion between the inhabitants of Northern and those of Southern Asia; and it is thus that India and Tibet have remained the only regions of this part of the world which have enjoyed the benefits of civilization, of the refinement of manners, and of the genius of the arts. The barbarians who, in the last agonies of the Roman Empire, invaded and devastated Europe, issued from the steppes and table-lands of Mongolia. As Humboldt says--"If intellectual culture has directed its course from the East to the West, like the vivifying light of the sun, barbarism at a later period followed the same route, when it threatened to plunge Europe again into darkness. A tawny race of shepherds of Thon-Klueu--that is to say, of Turkish origin, the Hioungum--inhabited, living under sheepskin tents, the elevated table-land of Gobi. Long formidable to the Chinese power, a portion of the Hioungum were driven south into Central Asia. The impulse thus given, uninterruptedly propagated itself to the primitive country of the Fins, on the banks of the Ural, whence irrupted a torrent of Huns, Avars, Chasars, and divers mixtures of Asiatic races. The armies of the Huns first appeared on the banks of the Volga, then in Pannonia, finally on the borders of the Marne and the Po, ravaging the beautiful plains where, from the time of Antwor, the genius of man had accumulated monuments upon monuments. Thus blew from the Mongolian desert a pestilential wind which, even as far as the Cisalpine plains, blighted the delicate flower of art, the object of cares so constant and so tender."[18] The temperature is extremely variable in these steppes, so that Madame de Bourboulon records having experienced in the morning a frost of one degree below zero, and some hours afterwards a heat of thirty degrees above zero (Centigrade). These changes are most numerous and most violent in the spring.