In these considerations which have been advanced we may find some reason for the early appearance of Neolithic man, as well as the fact that he advanced no farther in culture. But whether man first arrived in California in Pliocene times or not, he continued to inhabit the land to the present day. He would, however, be exposed to assault after assault from invading tribes. We do not wish to examine the question of the origin of the native Americans. It is held, by the best authorities, that at least a portion of them came from Asia, using the Kurile Islands as a stepping stone. Reaching the main-land of America, and passing down the coast, they would, sooner or later, reach the Valley of the Columbia—which has been characterized as the most extraordinary region on the face of the earth in the variety and amount of subsistence it afforded to tribes destitute of a knowledge of agriculture. At certain seasons of the year the rivers are crowded with fish, and they are then caught with the greatest ease. As a mixture of forest and prairie, the country is an excellent one for game. A species of bread-root grew on the prairies; and, in the Summer, there was a profusion of berries. To these advantages must be added that of a mild and equable climate.28 These combined advantages would make this valley one of the centers of population, from whence would issue successive bands of invading people. A portion of these, passing over into California, would come in contact with the descendants of Pliocene man. The result would be, that the primitive inhabitants, unable to escape to the west, would come in contact with wave after wave of invading tribes. This is not altogether theory. All inquirers into the customs, arts, and languages of the primitive Californians have been struck with the remarkable commingling of the same. We are driven to the conclusion that here has been the meeting ground of many distinct tribes and nations. “From such a mixture, and over-population of the most desirable portions of the country, would naturally result the formation of the hundreds of petty tribes that existed in both Upper and Lower California when first known to the Spaniards.”29