In the thirteenth century--that bright and luminous age, the time of Saint Thomas, of Saint Francis of Assisi, of Dante, of Saint Ferdinand--Russia was suddenly invaded by the Mongols, and, like locusts in a corn-field, those hideous and demoniacal foes fell upon her and made all Christendom tremble, so that the French historian Joinville records it as a sign of the coming of Antichrist. "For our sins the unknown nations covered our land," say the Russian chroniclers. Genghis Khan, after subduing all Asia, drew around him an immense number of tribes, and fell upon Russia with irresistible force, sowing the land with skulls as the flower of the field sows it with seeds, and compelling the once free and wealthy native Boyars to bring grist to the mill and serve their conquerors as slaves. The Russian towns and princes performed miracles of heroism, but in vain. The Tartar hordes, let loose upon those vast plains where their horses found abundant pasture, rolled over the land like an inundation. In a more varied country, more densely populated and with better communication, the Tartars would have been beaten back, as they were from Moravia. Again Nature's hand was upon the destinies of Russia; the topographical conditions laid her under the power of the Golden Horde. This great misfortune not only isolated Russia from the Occident and left her under Asiatic sway, but it also subjugated her to the growing autocracy of the Muscovite princes who were becoming formidable oppressors of their subjects, and they in turn were victims, tributaries, and vassals of the great Khans. So the invasion came to exercise a decisive influence upon the institutions of the future empire, pernicious in consequence of the abnormal development allowed to monarchical authority, and beneficent inasmuch as it aided forcibly in the formation of the nationality. At the time of the Mongol irruption Russia was composed of various independent principalities governed by the descendants of Rurik; the necessity of opposing the invader demonstrated the necessity also of uniting all under one sceptre. Continually chafing at the bit, dissimulating and temporizing with the enemy by means of clever diplomatic envoys, the princes slowly cemented their power and prepared the land for a homogeneous state, until one day the chivalrous Donskoï, the victor at the battle of the Don, opened the era of reconquest, exclaiming in the exuberance of his first triumph over the Tartars, "Their day is past, and God is with us!" But Russia's evil star awoke one of the greatest captains named in history, Tamerlane, who ruined the work begun by Donskoï, and toward the end of the fourteenth century once more laid the Muscovite people under subjection.