Thus far the most exact basis for the classification of these interesting people has been language. It was some time after the early intercourse with the natives of the East before the wide divergence in language was appreciated and all attempts to classify them fell into confusion. Finally, in 1836, Albert Gallatin began an arrangement by language which, reorganised by Powell, in 1885-86, has been generally adopted by ethnologists, and to-day, while not entirely approved, it is the only method that is satisfactory. By this system all tribes whose language roots are the same are classed together no matter how widely separated geographically they might have been. Notwithstanding the remarkable homogeneity of all the aboriginal inhabitants of the continent in customs, habits, and organisation, yet more than sixty separate stock languages were discovered in North America. Each one of these is taken to represent a "stock" group to which is given a title derived from Gallatin's first designation or from the leading tribe in that particular stock, with the addition of "an" or "ian," and all tribes having similar language roots are classed with this group or stock. Thus in the Siouan stock, the title is taken from the leading tribe, the Sioux, and all affiliated languages are brought under the same heading, as Dakota, Crow, Hidatsa, Iowa, Mandan, etc., and in the Athapascan the title is taken from the Athapascas of the far north, while the Apaches and Navajos of the south are classed under the same heading, as they speak related languages.[21] [Illustration: Umatilla Tipi of Rush Mats on Columbia River. From _Lewis & Clark_ by O. D. Wheeler.] [Illustration: Amerind Linguistic Map. After _Bu. of Eth. Seventh An. Rep._]