There is no more singular fact connected with the history of the Upper Yellowstone country than its long immunity from the presence of white men. From the date when Lewis and Clark first stood at the Three Forks of the Missouri, less than one hundred miles distant from this notable region, sixty-five years elapsed before it was fully known. In the meantime all the surrounding country had been thoroughly explored. Cities, villages, farms and highways had been established throughout the west. A railroad had been built across the continent. But around the head waters of the Yellowstone, the most attractive region of all, it was still _terra incognita_. A fact so remarkable requires adequate explanation. The most difficult feature of the question is the fact that no knowledge of this region appears ever to have been derived from the Indians. Lewis and Clark were told of the Great Falls of the Missouri, and of other notable geographical features, long before they saw them. But of the far more wonderful falls of the Yellowstone, of the great lake in the mountains, or of the marvelous volcanic phenomena in the same neighborhood, they received no hint. There is not a single instance on record, so far as we can discover, except in the meager facts noted in an earlier chapter, where rumors of this strange country appear to have fallen from the lips of Indians. And yet it was not a region unknown to them, for they had certainly passed back and forth across it for a long period in the past. Their deep silence concerning it is therefore no less remarkable than mysterious. But how was it that the long period of the fur trade should have passed without disclosing this country? To this question a more satisfactory answer may be returned. The Upper Yellowstone country was indeed, as we have seen, frequently visited in these early years. But it was never favorite territory. Old trappers say that, although it abounded in beaver, they were not so plentiful as in lower altitudes, while on the streams impregnated with mineral matter, the furs were not so good. The seasons also were unpropitious. The winter snows were so deep--they came so early and remained so late--that little could be done there except from the middle of June to the middle of September. But furs taken during the summer months are of inferior quality, and there was consequently no inducement to trap. Moreover it was generally at this time that the gatherings at posts and rendezvous took place, and after these were over but little time remained. Causes like these prevented extensive operations in this region, and doubtless only a comparatively small number of trappers ever saw it.