In what way does the use of indigenous words in "Part Three: Indian Territory" support the novel's themes?

In the first two parts of the novel, China Iron and Liz learn one another's languages as an important step in their friendship. In "Part Three: Indian Territory," China Iron begins to sprinkle more and more indigenous words into her narrative. This underscores the friendship she forms with the Iñchiñ but also makes a point about including the first peoples of Argentina in its national narrative.