This film made major concessions to political correctness in its portrayal of the Indians, who are depicted in a considerably more flattering light here than they are in Brian Moore's novel. This could also be considered the romanticizing "Dances With Wolves" effect. The novel drew some (unjust) criticism here in Canada for its uncompromising approach.
The actual history is fairly readily available. "The Jesuits in North America in the 17th Century" by the great American historian Francis Parkman is the standard 19th c. work on the proselytizing efforts of the French Récollet and Jesuit fathers.
Still, if you are not very familiar with the subject, this film is a strong, and quite gruesome, introduction. I'm not aware of a lot of films about the colonial period which are as tough. Not "Last of the Mohicans", or the adult westerns from the '50's, in my opinion. "Little Big Man", perhaps. Or possibly "A Man Called Horse", which I haven't seen. The priest in the story is a composite of actual missionaries, and the impact of this historical adventure thriller is heightened for me knowing that everything in this film happened, and often a whole lot worse.
The rights and wrongs, the pros and cons, of the cultural collision of Europeans with the autochthonous peoples are still too contentious, so I would rather not get into them. There is a lot here to brood about afterwards, and chances are good that you'll seek out a copy of the novel -- it's not very long, and a lot easier to read than James Fenimore Cooper. If you're American or Canadian, this is an important part of our shared past.
"Black Robe" is one of the very best Canadian feature films, with a solid cast led by Lothaire Bluteau with August Schellenberg and Tantoo Cardinal in support. The presence of an Australian director, Bruce Beresford, perhaps kept the film from turning into a well-meaning but dry Canadian history lesson.