I´ve found the film we´ve talked about on Youtube, just in case anyone wants to have a look on it. It's about an episode of the British domination of Sudan: the Sudanese Arabs, headed by Muhammmad Ahmad, know as the Mahdi, revolted againts the British rule and started fighting for their independence. The British government sent an army commanded by General Charles Gordon to defend the city of Khartoum. The film shows the Western version of the story: Gordon is represented as a hero and the Mahdi and his supporters are depicted as zealots.
Here you have a short review of the film: