The theme of the demise of a traditional way of life, as seen in Pollock's Walsh, pertains primarily to the Native Americans of the U.S., as well as the indigenous tribes of Canada, (though Walsh also experiences it).
At the start of Act One, Walsh is studying the contents of supplies shipped to Fort Walsh. The boxes are filled with farming "implements." Walsh, who knows the tribal people of Canada better than the British government that rules the territory, recognizes this as a waste of resources:
Are you telling me, man, that once again the government has seen fit to burden me and the natives of these parts with another load of seed and equipment to rot and rust when they know...because I've told them time and again, that these Indians are not, and will never be, farmers!
The British government is trying to make the Indians self-sufficient, but the reader does not get the sense that it is for the best interest of the native population, but more so the government does not need to feed them. This will be the issue when the Sioux and Sitting Bull arrive—for a time. (Later, it becomes a political matter: keeping food and any way to hunt it--with ammunition—away from the Indians in order to force them out of Canada.)
The demise of the traditional way of life is also seen when Crow Eagle takes one of Mrs. Anderson's washtubs to make a drum. In the past, the Indians would have found what they needed in the environment to make a drum, but in living at Fort Walsh, they are unable to do so. Crow Eagle sees that she has two tubs and takes one.
Mrs. Anderson represents the white society that has little regard for the Indians. For Indians who lived off of the land, they used everything without waste, but never took more than they needed. Walsh must explain the unfamiliar behavior of the whites wanted more than they needed:
They need even what they appear not to need...
This alien way of life is hard for the Indians to grasp; it shows again how their way of life is disappearing. Walsh makes an attempt to explain the need for the Indians to change:
When the white man comes, the buffalo goes...And with the buffalo goes the life you have known...That is why the Great White Mother [Queen Victoria] sends you these [the farming implements]...
I do not wish to be servant to a cow.
Change is very hard. Louis points out to Walsh:
Ever since he was born he has eaten wild meat...He cannot give up quickly the customs of his fathers.
The demise of a traditional way of life is evident as Sitting Bull and Gall report the attack of the whites against them without provocation, and especially Custer's attack at the Little Big Horn. Gall reports that they simply defended themselves and their families against the U.S. Army's attempt to "[eliminate] the savage" (as Terry says), and now they are "hunted like the animals we hunt." Sitting Bull talks of their home, the Black Hills. And while his tribe has taken no money, nor has it signed any documents relinquishing their claim to the land, it has been taken from them: land that has been in his family for years, to be passed on this his children.
The change is also seen in how the Indians are being driven away and killed. There is no peace for them any longer. Sitting Bull remembers a time when the Sioux "owned the world," as far as they could see. Their 10,000 warriors are now dead. Their way of life is being systematically destroyed, in turn wiping out their race.