(sorry for my bad english)
I'd say Urga is more than a classic, its sort of one-of-its-kind, but I kept thinking about similar movies and found only one:
Kurosawa's Dersu Uzala (1975) http://www.imdb.com/title/tt0071411/
Both deal with the cultural differences, in a very visual, close-to-nature style. Although Dersu Uzala shows the humans and natures relation on a more emphatic and detailed basis, and its also less artsy, but still I felt like both movies told: no matter how easy it seems to step trough cultural borders, failure is a possibility.
-both movies show smooth transitions between the cultures in a material form: the TV, or conserve food in Urga, and the gun the nomad uses in Dersu Uzala.
-at the same time, the rejection of the modern culture is also shown, in form of the turn-down condoms, and the child-birth laws, or as in Dersu Uzala, complete rejection of modern culture.
If you fell in love with Urga, you should watch Dersu Uzala, im sure you will enjoy it.
Do you know about any similar movies? please tell me if you have any!