Barren Lives

In 1940, a poor family from Brazil's drought-stricken Northeast, the cowherd Fabiano, his wife Sinhá Vitória, their two young sons and their dog Baleia, crosses the sertão on foot in search of work and food. Fabiano is hired by a ranch owner and falls into debt with him, and after a soldier provokes him into a card game he is beaten and jailed. When the drought returns, the family sets out once more across the barren land. Based on Graciliano Ramos's 1938 novel, the film is one of the key works of the Brazilian Cinema Novo movement and was entered into the 1964 Cannes Film Festival, according to Wikipedia.

Note on sources: Wikipedia says the film was entered into the 1964 Cannes Film Festival, while DVD Talk says it won the OCIC Award at Cannes in 1963; the Festival de Cannes website lists it in a 2004 Cannes Classics tribute.