Every family is possessed of a flock of sheep and goats, sometimes numbering many thousands, and a band of horses, generally several hundreds, in a few instances several thousands.  In recent times many possess small herds of cattle, the progeny of those which strayed into the reservation from the numerous large herds in its vicinity, or were picked up about the borders by some Navaho whose thrift was more highly developed than his honesty.  The condition of the tribe, as a whole, is not only far removed from hardship, but may even be said to be one of comparative affluence.

Owing to the scarcity of grass over most of the country, and the difficulty of procuring a sufficient supply of water, the flocks must be moved from place to place at quite frequent intervals.  This condition more than any other has worked against the erection of permanent houses.  Yet the Navaho are by no means nomads, and the region within which a given family moves back and forth is extremely circumscribed.

In a general way the movements of a family are regulated by the condition of the grass and the supply of water.  In a dry season many of the small springs cease to flow at an early date in the summer.  Moreover, if a flock is kept too long in one locality, the grass is almost destroyed by close cropping, forcing the abandonment of that particular place for two or three years.  When this occurs, the place will recover and the grass become good again if left entirely undisturbed for several years.

The usual practice is to take the flocks up into the mountains or on the high plateaus during the summer, quartering them near some spring or small stream, and when the snow comes they are moved down to the lower foothills or out into the valleys.  In the winter both shepherds and sheep depend on the snow for their water supply, and by this means an immense tract of country, which otherwise would be a perfect waste, is utilized.  As the snow disappears from the valleys the flocks are gradually driven back again into the mountains.

The heavy fall of snow in the mountains and its slow melting in spring makes that region far more fertile and grassy than the valleys, and were it possible to remain there throughout the year doubtless many families would do so.  As it is, however, the feed is covered too deeply for the sheep to reach it, and during several months heavy snowdrifts make communication very difficult and at times impossible.  In a few favored localities—­usually small, well-sheltered valleys here and there in the mountains—­some families may remain throughout the winter, but as a rule, at the first approach of the cold season and before the first snow flies there is a general exodus to the low-lying valleys and the low mesa regions, and the mountains are practically abandoned for a time.