The film begins with a reenactment of the gruesome events of cannibalism as described by the prosecuting attorney during Alferd Packer's trial in 1883. Packer insists that things happened differently than what has been recounted, and begins to tell his story to journalist Polly Pry (Toddy Walters) through flashback.
Eventually, the Packer party is spotted by two “Nihonjin” Indians (obviously played by Asians and speaking Japanese). They are taken back to the tribe where they learn the trappers are waiting for the winter storm to pass as recommended by the chief.
The Japanese "Indians" were really Japanese foreign exchange students from Trey Parker's college. The Indian chief was played by the owner and operator of "Sushi Zanmai" in downtown Boulder, CO.
Said Indians are referred to as the Nihonjin tribe. "Nihonjin" is Japanese for "Japanese people."
Comment: I guess this is supposed to be funny? Maybe this is the dramatic, unfunny, part of the movie.
So Trey Parker used the standard chief and teepee stereotypes for Utah's Ute Indians. And he compounded the problem by using Japanese people to play the Indians.
This fits nicely with the anti-Indian prejudice shown in the South Park episode Red Man's Greed. The evidence mounts that Parker has a racist attitude toward Indians.
For more on the subject, see The Best Indian Movies.