Copper Defines the Time Vaguely

(7) It is not improbable that the Mongols were beginning to move west and south nearly ten thousand years before our era. Their eastern movement into China may not have been long after. But their northward migrations must have been considerably later; the northern route remained open longer for the megalithic peoples from the West; for some of them reached the Pacific without copper, and afterwards, when forced off the coasts, reached Polynesia without any trace of that metal. And the age of copper in Northern Asia goes back four or five thousand years before our era; it was early there, because the Ural-Altai region was one of the great sources of the primitive world's copper.

(8) But copper, next to the precious metals, is the most uncertain for defining a period. The tools or weapons made out of it are soft, and turn before the task of cutting or hewing. They are not to be compared for efficiency to the flint or obsidian knives and axes of the stone period. Primitive man did not seize on it with avidity. A copper age exists with any definiteness only in a few regions, and even there has but vague limits. But before the megalithic drift eastwards had stopped on the northern route, that metal had come into use; for it is found in the kurgans or mound-graves page 43of the Tchudes, that mythical people to whom the Northern Mongols attribute everything they cannot explain the origin of.