Exxcllent South American film about 2 ethnographers exploring the rain forest - 30 years apart

The Embrace of the Serpent looks like the kind of film that Werner Herzog might have made (he didn't; it's by a team from Colombia), an ethnographic drama that follows two anthropologist/explorers in South America (undefined rain-forest area, could be Columbia or Brazil), two stories told in tandem: the first is of a German man interested in learning about and preserving the native cultures, brought by a native Indian who is slightly westernized (wearing the same type of tropical khakis as the German) to an Indian shaman and healer who seems to be living alone in the jungle - angry and resentful about the way white settlers have taken over tribal land and corrupted (or killed) native people. The native man agrees to a river journey to find healing medicines for the German. In the parallel story, set about 30 years later (the 1940s) an American, having read the posthumous journals of the German ethnographer, locates the same native healer and asks him to help him find a tree of great value - he agrees, and the go on a river journey the recapitulates the earlier journey 3 decades later and we see some of the increasing devastation and native people are enslaved and oppressed. There are some very beautiful scenes (movie shot in b/w widescreen, except for 1 sequence) and some harrowing moments, particularly the 2 visits to a Catholic school for boys - later corrupted into a Jim Jones-type settlement. Late in the movie we learn that what the American is seeking isn't some powerful hallucinogen but a rare form of rubber tree - something desperately needed - and highly valuable - at the start of WW2. A totally engaging and often weird movie, and we learn at the end - but good to know at the outset - that it's based on the actual journals and papers of the two white explorer/ethnographers/exploiters.