time the first summer floods arrive.

The Indians of the Great Plains lived a very different life from
that of the natives of either the mountains or the Pacific coast.
In the far north, to be sure, the rigorous climate caused all the
Indians to live practically alike, whether in the Rockies, the
plains, or the Laurentian highland. South of them, in that great
central expanse stretching from the latitude of Lake Winnipeg to
the Rio Grande River, the Indians of the plains possessed a
relatively uniform type of life peculiar to themselves. This
individuality was due partly to the luxuriant carpet of grass
which covered the plains and partly to the supply of animal food
afforded by the vast herds of buffaloes which roamed in tens of
thousands throughout the whole territory. The grass was important
chiefly because it prevented the Indians from engaging in
agriculture, for it must never be forgotten that the Indians had
neither iron tools nor beasts of burden to aid them in overcoming
the natural difficulties in the way of agriculture. To be sure,
they did occasionally pound meteoric iron into useful implements,
but this substance was so rare that probably not one Indian in a
hundred had ever seen a piece. The Indians were quite familiar
with copper, but there is not the slightest evidence that they
had discovered any means of hardening it. Metals played no real
part in the life of any of the Indians of America, and without
such tools as iron spades and hoes it was impossible for them to
cultivate grassland. If they burned the prairie and dropped seeds
into holes, the corn or beans which they thus planted were sure
to be choked by the quickly springing grass. To dig away the
tough sod around the hole for each seed would require an almost
incredible amount of work even with iron tools. To accomplish