THE CASPIAN SEA AND ITS NEIGHBORS 339
they would still have to meet the losses incident to a course of nearly four hundred miles through the sandy desert without reinforcement from tributaries before reaching the Caspian. On the way, they would have to maintain a lake in the depression of Sari-Kamish (Yellow-Reeds), which lies in the course of the old Uz-boi channel, for its bottom is fifty feet below the level of the Caspian Sea. Having met all the losses, the united streams would by no means be able to add 26,000 square miles to the water-spread of the Caspian. The inferred expansion, however, amounted to far more than this. Apparently, we must either disregard the ancient authorities entirely, or else admit a change of climate. The climatic hypothesis is supported not only by the agreement of the phenomena of the Caspian with those of distant regions, but by the fact that ruins such as those of Mery and Bal Kuwi, which are now inadequately supplied with water, appear to be typical of many in the Aralo-Caspian basin, where streams have diminished in size during historic times.
Returning once more to our investigation of the varying level of the Caspian Sea, we find a surprising change between the conditions in the first century of the Christian era and those of four or five centuries later. Near the beginning of our era, the trade route from Europe to India altered its course, as did the one from China to the `Vest. It ceased to go up the Oxus, perhaps because the Caspian had so far contracted that the river no longer reached that sea, but fell into the now isolated Sea of Aral. The new route crossed from the mouth of the Cyrus River to the southwest corner of the Caspian, where in time there grew up a flourishing
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