One might suppose that under such circumstances the Indians would merely clear another patch of forest not far from the village and so continue to live in the old place. This, however, they did not do because the labor of making a clearing with stone axes and by the slow process of girdling and burning the trees was so great that it was possible only in certain favored spots where by accident the growth was less dense than usual. When once a clearing became grassy, the only thing to do was to hunt for a new site, prepare a clearing, and then move the village. This was apparently the reason why the Iroquois, although successful in other ways, failed to establish permanent towns like those of the Pueblos and the Haidas. Their advancement not only in architecture but in many of the most important elements of civilization was for this reason greatly delayed. There was little to stimulate them to improve the land to which they were attached, for they knew that soon they would have to move. Farther south the character of the grassy vegetation changes, and the condition of agriculture alters with it. The grass ceases to have that thick, close, turfy quality which we admire so much in the fields of the north, and it begins to grow in bunches. Often a southern hillside may appear from a distance to be as densely covered with grass as a New England hayfield. On closer examination, however, the growth is seen to consist of individual bunches which can easily be pulled up, so that among the southern tribes the fields did not become filled with grass as they did in the north, for the women had relatively little difficulty in keeping out this kind of weed as well as others.