Unknown to these southern plainsmen, after a time the plains were invaded from the north as well. Bands of the northern Wood Indians, first perhaps the Blackfeet, long afterwards the Crees, began to creep out on the prairie. Like the southern Sioux, they could not travel fast on land; the Indians had no horses. Ages before the first men came there had been horses here, at first of a dwarfish kind, with three toes. The horse tribe may have had its beginning here and spread over to Asia when the sea between Siberia and Alaska was dry land; but nothing was left of them in all America except their fossil bones. To be sure, the Indians had dogs; but at first these were only camp-followers, and their only use was to be killed and eaten when better meat was scarce. In the far north, the Eskimo learned to hitch dog teams to a sleigh; and presently the Indians south of them put their dogs in harness, too. The Wood Indians, living in a country full of lakes and rivers, in summer did all their travelling by canoe. In winter they stayed idle in camp, down in some sheltered valley or forest glade, living in rough shelters or tents of birch-bark or caribou hide. Presently, when they came out into the open to follow the buffalo, they had to leave their canoes behind. They did not like carrying loads on their backs; and one day an Indian, no lazier than the rest, but with more active brains, thought of a new way to make the dogs do that work. They had already been trained to haul toboggans in winter, and sometimes in summer; but the toboggan is a poor sort of cart except when it has smooth snow for its flat surface to glide over. To be sure, the travoy was not very much better, but it was less easily upset, and as the Indian never thought of inventing wheels let us give him all credit for inventing the travoy. You have probably seen it in action,—two poles crossed over the dog’s back, and trailing wide apart behind, with cross-pieces to carry the load. To these Indians spreading slowly over the prairie from the north, the buffalo was everything, as it was to the plainsmen of the south. They made their tents of its skin. They lived on its meat, though when the pemmican gave out and no herd was near they ate rabbit, gopher, beaver, crow, dog, anything and everything they could get. As for vegetable food, they were content with berries and roots, especially the “pomme blanche” or prairie turnip, which the women scraped and dried for winter use. The early explorers found the Mandans of the Missouri growing corn and tobacco, beans and pumpkins, and sunflower—for the seed,—with a hoe made of the buffalo’s shoulder-blade and a wooden handle; but the prairie Indians as a whole despised farming.