The connection, nay partial identity, of this culture with that of the Thompson River region in the southern interior of British Columbia is supported by considerable evidence. Small heaps of fresh-water clam shells are found in both regions. The preponderance of chipped points over those ground out of stone, bone and antler; the presence of digging stick handles; pestles with flaring bodies and no striking heads, others with tops in the form of animal heads; celts; the sites of cache pits, of circular summer lodges marked by rings of stones; and of semi-subterranean houses with stones on the encircling ridge; pairs of arrow-shaft smoothers, and bone tubes, were all found to be common to both regions. The simple pipe bowl found here, although with one exception not found among archaeological objects in the Thompson area is commonly used by the present Indians there. Tubular pipes, modern copper tubes or beads, incised designs consisting of a circle with a dot in it and engraved dentalium shells, each of a particular kind, besides pictographs in red, rock-slide sepulchres, modern graves walled up with parts of canoes, the marking of recent graves with sticks, and the custom of burying artifacts with the dead were also found to be common to both areas. Perforated slate tablets of gorget-form are unknown in both regions. Circles of stones which mark places where cremated human remains were found in this region sometimes indicate graves in the Thompson River region.

Frazer[432] mentions meeting Yakima Indians in the Lillooet Valley which shows that they travelled even beyond the Thompson River country and readily accounts for the dissemination of cultural elements.

On the other hand, many differences in culture are observable. Thus objects made of nephrite and mica which occur, the former being common in the Thompson River valley, were not found in the Yakima area. Quarries and terraced rock-slides such as were seen here are not known to us in the Thompson River region. The bone of the whale occasionally found in the Thompson River country is lacking in Yakima collections. That glassy basalt was not the chief material for chipped implements, as it was in the Thompson River region, is probably due to the scarcity of this material and its use is perhaps as rare in the Yakima valley as on the coast. Chipped implements were made of a greater variety of stone than in the interior of British Columbia, and a greater proportion were of the more beautifully colored materials. No harpoon points made of a unio (?) shell, such as the object found in the Thompson River region or other objects made of such a shell, were seen. Notched sinkers and large grooved sinkers were more commonly found than in the Thompson Valley, while sap scrapers which were common there, were not found in the Yakima district. A great number of pestles made from short cylindrical pebbles, forming a type rather rare in the Thompson River region; many long pestles, of which only four or five have been found in interior British Columbia; and one with a zigzag design not represented among the finds from that region, were found in the Yakima area. Saucer-shaped depressions marking summer lodge sites were not noted by the writer. Clubs made of stone were more numerous and all are of a different type. Clubs or other objects made of the bone of the whale or drilled pendants either circular or elongated were not found. Petroglyphs, pictographs in white, and representations of feather headdresses were not found among the archaeological objects in the Thompson region. Graves in knolls, some with a cyst made of thin slabs of stones constitute another distinct trait of the Yakima area.

There is relatively less evidence of contact with the prehistoric people of Puget Sound and the Pacific coast of Washington, and of southern British Columbia. Several kinds of sea shells, including dentalium, haliotis and pectunculus, which must have come from the coast, were found in the Yakima Valley. Small points chipped from beautiful material found in this region were occasionally seen on the coast, more particularly south of Puget Sound. Glassy basalt was used here perhaps about as much as on the coast. Net sinkers are also about as common here as on the coast from Gray's Harbor southward. The pestles found in the vicinity of Vancouver Island are similar to some of the short pestles found in the Yakima region. Short tubular pipes are found on the coast in the vicinity of the Saanich Peninsula and the Lower Frazer. The pipe previously described as clearly representative of the art of the Northwest coast must have been brought from there or made by a coast artist, not by one merely familiar with the art of the coast. A portion of the material indicative of coast culture that was found in the Yakima Valley may have come up the Cowlitz and down the Toppenish River.

The similarities mentioned are, however, outweighed by marked differences. Large shell heaps—the chief feature of Coastal archaeology—have not been found in the Yakima area, while quarries are unknown to us on the coast. Objects made of nephrite and whale's bone are lacking in the Yakima Valley. A very great number of points rubbed out of slate and bone are found on the coast, but none rubbed out of slate and only a few rubbed out of bone have been found on Yakima sites. Net sinkers are much more common than on the coast, where they are plentiful only from Gray's Harbor southward and in the Lower Columbia Valley. Long pestles with the tops carved to represent animal heads are distinctive of the Yakima area, while cylindrical pebbles used as pestles but slightly changed from the natural form, which are quite common in the Yakima Valley, are rarely found in the Coast country. One style of club made of stone commonly found in this vicinity has not been seen anywhere on the coast, although some clubs made of stone are like specimens from that region. Perforated slate tablets like Coastal gorgets are unknown to us from the Yakima area. Cairns common on the coast are not found in the Yakima country, while the reverse holds true of rock-slide burials. Graves in knolls are unknown on the Pacific, and artifacts are often found in the Yakima graves but they seldom, if ever, occur with ancient burials on the coast.

Much of the material from the Yakima region resembles that which I have seen from the general area including the Columbia Valley between Umatilla and The Dalles, and possibly extending further down the valley. There seems to be a greater similarity of the art products of the Yakima to those of the Thompson River region than to those of the Columbia Valley below the mouth of the Snake, so far as we understand the latter region at this time, and this according to Lewis[433] is certainly not contrary to the belief in an earlier occupancy of this region by the Salish. The culture here resembles that of the Nez Perce region to the east in that a considerable variety of material was used for chipped implements.[434]

Inter-tribal trade may have been a factor in the production of some observed similarities. It was seen that pipes of three types, one of which is found as far east as the Dakota, another as far north as the Thompson River country, and a third as far west as the Queen Charlotte Islands are all found in this region. It is clear that the ancient people from the Yakima region had extensive communications not only with the region southward as far as The Dalles, but also northward, as far as the more distant Thompson River tribes. If the products of the sea found in this region came up the Columbia, as may be inferred from Lewis,[435] it is a good illustration of how trade as a rule, follows the line of least physical resistance; although the migrations of the tribes do not always follow such lines because the lines of trade as a rule are thickly populated by people who resist the migration of their neighbors. Lewis[436] states that from the coast inward there was only one trade route of importance in the Washington-Oregon-Idaho region and this led up the Columbia River to The Dalles where was found the greatest trade center in the whole region and whither the tribes were wont to come from the north and south as well as from the east.[437] Klamath,[438] Cayuse, Nez Perce, Walla Walla and other Sahaptin and probably Salish tribes were all in the habit of going there to traffic. He also states that further east, the Sahaptin in their turn, traded with the Shoshone from whom they obtained buffalo robes and meat. The center for this trade at least in later times was the Grande Ronde in eastern Oregon;[439] but this later center probably came into being after the advent of the horse. The Okanogan are known to have crossed the mountains to Puget Sound to trade wild hemp for sea shells especially dentalia as well as for other small objects.[440] The Yakima also in later times crossed the mountains and traded with Puget Sound tribes according to Gibbs,[441] but if this trade were carried on in earlier times its effect in the Yakima Valley seems to have been slight as indicated by the few dentalium shells, the shell pendants shown in Figs. 87-94 and the pipe of coast art, shown in Fig. 127. It is possible that this trade with the coast became customary only after the horse was introduced. There was a considerable amount of trade between the Yakima and the Thompson River and other tribes of British Columbia which was carried on chiefly through the Okanogan.[442] Lewis[443] states that the Walla Walla who lived to the south of the Yakima at least in later times visited as far north as the Thompson River region, and that certain Sahaptin tribes seem to have moved northward and westward and forced back the Salish tribes which at the time of Lewis and Clark's visit were on the north bank of the Columbia and on its tributaries.[444] These tribes were particularly the Klickitat and the Yakima, an assumption which Lewis states is supported by the definite assertions of the natives themselves. A number of old men positively assured Dr. Suckley that they had pushed their way into the country formerly occupied by the Salish.[445] The Klickitat, although living in a well wooded region on the southern slopes of Mt. Adams and Mt. St. Helens are thought to have been driven by the Cayuse from their earlier home which was further east and south. Later, they went further west into the Cowlitz Valley.[446] This may account for the circular pit surrounded by an embankment which I saw near Rochester in Thurston County and interpreted as the remains of a semi-subterranean winter house site. Lewis also states that the Yakima probably lived on the Columbia near the mouth of the river which now bears their name, and are in fact so located by Cox who places them on the north and east side of the Columbia. The pressure of neighboring tribes caused by the coming of the white race no doubt facilitated the adoption of new cultural details.

As late as 1854, the Palus, a tribe living further east on the Paloose River regarded themselves as a portion of the Yakima and the head chief of the Yakima as their chief.[447] The general similarity of the Walla Walla language to that of the Klickitat and Yakima rather than to that of the Nez Perce is mentioned by Lewis.

Cultural elements, especially those associated with the horse and with the new mode of life which it made possible, probably came from the region to the southeast, and show a great similarity to the Plains type of culture. How much the Plains culture had influenced the Plateau type before the introduction of the horse, is a question.[448] On the Columbia River, near the mouth of the Yakima, were numerous Indians who were visited by Clark in 1805, but he says that while he saw a few horses, the Indians appeared to make but little use of them. If these were the Yakima Indians there must have been quite a change in their manner of living in the next few years.[449] This agrees very well with the time of the introduction of the horse among the Lower Thompson Indians towards the close of the eighteenth century, according to Teit.[450] All this would tend to show that the horse, while common in the Yakima country, about that time, had not yet affected the earlier customs of the natives.

The early culture throughout the great area of which this is a part, according to Lewis, was of a very simple and undeveloped character, which probably accounts for the rapidity with which eastern types were assimilated when once introduced.[451]

Summing up: the prehistoric culture of the Yakima area resembled that of its recent inhabitants, as it will be remembered was the case in the Thompson River region, the Lower Fraser Valley and the Puget Sound country including the coast from Comox on Vancouver Island to Olympia. As a typical plateau culture, being affiliated with the neighboring cultures to the north, east and south, it presented a sharp contrast to both the present and past cultures of the coast to the west. Compared with other branches of the Plateau culture area it must be considered inferior in complexity to its northern neighbor of the southern interior of British Columbia and also to the adjacent branch near The Dalles to the south. While each of these divisions has been influenced by the others more especially in the past, differentiations due to environment or specific historical conditions lead to local variations without obscuring an essential unity of cultural traits.