Unlike The Indian Fighter (which was rife with historical inaccuracies), A Man Called Horse attempted to be very accurate with respect to costume design, languages, marriage ceremonies, etc, such as the film's representation of tribal practices and rituals (including the Sun Dance) is shown as based upon historical records.
The film makers evidently wanted to be as historically accurate as possible and you can tell by the level of detail that they tried the best they could. As such the film is largely about Native customs and rituals.
It is still however a white man's fantasy story - but hey, what can you expect for a film made in 1970? Only 10 years earlier John Wayne films was still shooting Natives as savages. In contrast this film treats both Natives and white men equally - which is more than can be said about many earlier films.
There was also two sequels made, both starring Richard Harris. The Return of a Man Called Horse (1976); Triumphs of a Man Called Horse (1983).
4 stars out of 5.