Barmak, who was not able to work in his country after the Taliban came to power in 1996, tells the story of the social situation in Afghanistan at the time, with a focus on women and their lack of status in society.
The film, named after Usama bin Ladin, who at the time was established in Afghanistan, was also greeted with enthusiasm at the Cannes Film Festival last spring.
The jury's special mention went to the Moroccan movie Les Fibres de l'ame (The Soul's Fibres), the first feature of Hakim Belabbes which was also well received in Venice last month.
Another Moroccan movie, Les Yeux Secs (The Dry Eyes) of female director Narjis Najjar won the award given by the public.
Depuis Qu'Otar est Parti (Since Otar Left) of French director Julie Bertucelli and Georgian director Bernard Renucci obtained the prize for best screenplay, an award presented by the Canadian Broadcasting Corporation.
The jury also gave a special mention to Quebec directors Claude Fortin and Serge Laprade for their script of the movie 100% Bio on the life of a former TV star, turned presenter of infomercials.
The 32nd edition of the Montreal festival, one of the largest in Canada, on Sunday also paid tribute to Iranian cinema as well as to German director Werner Herzog and British director Peter Greenaway, who released the third part of his Tulse Luper Suitcases trilogy last week.