FOR THE THOUSANDS of American Indians who will march in procession to the beautiful new museum on the Mall today, this is in part a homecoming. Centuries before there was a capital or a nation, a Congress or a Constitution, human society thrived here. There is evidence of numerous quarries for tools and hunting implements in the area where Piney Branch Road now meets 16th Street in Northwest, and of more of them near the site where the Tenleytown Metro station was dug; of villages densely clustered along the path of the Southeast Freeway as well as on the banks of the Potomac River where the C&O Canal towpath and the Capital Crescent Trail now run. Indeed, "the evidence from the surrounding region strongly suggests that this area has been occupied by human groups ever since the end of the Pleistocene era, 10,000 to 20,000 years ago," wrote Robert L. Humphrey and Mary Elizabeth Chambers in the George Washington University monograph "Ancient Washington." One archeological dig has been done practically in the center of the Mall.

Most traces of those societies have been buried by the centuries or even millennia, the villages destroyed or dispersed. And yet hundreds in this region still claim descent from the Piscataway and other peoples whose way of life seemed to have ended with the coming of Europeans. They stand -- they live -- as examples of what the director of the National Museum of the American Indian, W. Richard West Jr., likes to call "survivance" -- a word conveying what he sees as the museum's primary purpose: "to demonstrate the continuing existence and vitality of native people and cultures."

That existence and vitality are captured in Indian art, artifacts and music, and in the customs, ceremonies and everyday activities of the millions of indigenous peoples of North and South America. The tribes and groups that will appear in the large spaces given over to public assemblies and performances promise a dizzying array of activities reflecting the diversity of thousands of Indian people.

Mr. West says the museum will not try to paper over controversy as it deals with the clash and encounter of native and European societies. Given that long history of warfare, massacre, conquest and coexistence -- as well as the social problems that have plagued many Indian communities -- we can expect a stink or two to be raised in the years to come over some exhibit or other. But the greatest and most encouraging attributes of the museum are the confident self-assertion of the people it portrays and the avid welcome it is receiving in the nation's capital.

The story to be told in this place is one of remarkable cohesion, adherence to tradition and spiritual awareness -- reverence for places, the sacredness of inanimate objects. It's not a mode of thinking that seems likely to catch on in hard-bitten Washington, but then, this is a museum, not a place where you go for a conversion experience. It will be enough for now if it causes some of us to stop once in a while, say, upon sighting a deer in Rock Creek Park or a blue heron by the Potomac, and think a little about the person who might have looked up from her work a thousand years ago in the same place, and seen much the same thing.