There were vast regions of unexplored land. The civilized kingdoms, though enormous in extent, occupied a comparatively small portion of the whole planet. Valusia was the western-most kingdom of the Thurian Continent; Grondar the eastern-most. East of Grondar, whose people were less highly cultured than those of their kindred kingdoms, stretched a wild and barren expanse of deserts. Among the less arid stretches of desert, in the jungles, and among the mountains, lived scattered clans and tribes of primitive savages. Far to the south there was a mysterious civilization, unconnected with the Thurian culture, and apparently pre-human in its nature. On the far-eastern shores of the Continent there lived another race, human, but mysterious and non-Thurian, with which the Lemurians from time to time came in contact. They apparently came from a shadowy and nameless continent lying somewhere east of the Lemurian Islands. The Thurian civilization was crumbling; their armies were composed largely of barbarian mercenaries. Picts, Atlanteans and Lemurians were their generals, their statesmen, often their kings. Of the bickerings of the kingdoms, and the wars between Valusia and Commoria, as well as the conquests by which the Atlanteans founded a kingdom on the mainland, there were more legends than accurate history. Then the Cataclysm rocked the world. Atlantis and Lemuria sank, and the Pictish Islands were heaved up to form the mountain peaks of a new continent. Sections of the Thurian Continent vanished under the waves, or sinking, formed great inland lakes and seas. Volcanoes broke forth and terrific earthquakes shook down the shining cities of the empires. Whole nations were blotted out. The barbarians fared a little better than the civilized races. The inhabitants of the Pictish Islands were destroyed, but a great colony of them, settled among the mountains of Valusia's southern frontier to serve as a buffer against foreign invasion, was untouched. The Continental kingdom of the Atlanteans likewise escaped the common ruin, and to it came thousands of their tribesmen in ships from the sinking land. Many Lemurians escaped to the eastern coast of the Thurian Continent, which was comparatively untouched. There they were enslaved by the ancient race which already dwelt there, and their history, for thousands of years, is a history of brutal servitude.