There was no such thing, at that time, as a consolidated Nordic empire. As always, the tribes had each its own chief or king, and they fought savagely among themselves. What their destiny might have been will not be known, because another terrific convulsion of the earth, carving out the lands as they are known to moderns, hurled all into chaos again. Great strips of the western coast sank; Vanaheim and western Asgard--uninhabited and glacier-haunted wastes for a hundred years--vanished beneath the waves. The ocean flowed around the mountains of western Cimmeria to form the North Sea; these mountains became the islands later known as England, Scotland and Ireland, and the waves rolled over what had been the Pictish wilderness and the Bossonian marches. In the north the Baltic Sea was formed, cutting Asgard into the peninsulas later known as Norway, Sweden and Denmark, and far to the south the Stygian continent was broken away from the rest of the world, on the line of cleavage formed by the river Nilus in its westward trend. Over Argos, western Koth and the western lands of Shem, washed the blue ocean men later called the Mediterranean. But where land sank elsewhere, a vast expanse west of Stygia rose out of the waves, forming the whole western half of the continent of Africa. The buckling of the land thrust up great mountain ranges in the central part of the northern continent. Whole Nordic tribes were blotted out, and the rest retreated eastward. The territory about the slowly drying inland sea was not affected, and there, on the western shores, the Nordic tribes began a pastoral existence, living in more or less peace with the Cimmerians, and gradually mixing with them. In the west the remnants of the Picts, reduced by the cataclysm once more to the status of stone-age savages, began, with the incredible virility of their race, once more to possess the land, until, at a later age, they were overthrown by the westward drift of the Cimmerians and Nordics. This was so long after the breaking-up of the continent that only meaningless legends told of former empires. This drift comes within the reach of modern history and need not be repeated. It resulted from a growing population which thronged the steppes west of the inland sea--which still later, much reduced in size, was known as the Caspian--to such an extent that migration became an economic necessity. The tribes moved southward, northward and westward, into those lands now known as India, Asia Minor and central and western Europe.