The sequel was a result of Arcand's longtime desire to make a film about a character close to death, also incorporating a response to the September 11 attacks of 2001. It was produced by companies from both Canada and France, and shot mainly in Montreal, also employing a former hospital and property near Lake Memphremagog.
Seventeen years after the events of The Decline of the American Empire, Sébastien is enjoying a successful career in quantitative finance in London when he receives a call from his mother, Louise, that his father and Louise's ex-husband Rémy is terminally ill with cancer. Sébastien is not enthused about seeing Rémy, whom he blames for breaking up the family with his many adulteries. Rémy and his friends of the older generation are still largely social-democrats and proponents of Quebec nationalism, positions seeming somewhat anachronistic long after the Quiet Revolution of the 1960s. Rémy does not like Sébastien's career, lack of reading or fondness for video games.
The father and son travel to the U.S. state of Vermont to briefly receive medical care before returning to the overcrowded and disorganized Quebec hospital. Sébastien attempts to bribe hospital administration for better care, and calls Rémy's old friends about a possible visit. Upon hearing heroin is "800%" more effective than morphine, he tracks some down for Rémy from a drug addict, Nathalie.
Meanwhile, Rémy is reunited with his friends, including Pierre, Dominique, Claude and Diane, Nathalie's mother, and they share a conversation on their old sex drive and the gradual decline of their vitality. Diane is concerned for Nathalie, while Rémy, a history professor, lectures the hospital chaplain Constance on the relative peace of the 20th century compared to past centuries. At the same time, another scholar describes the September 11 attacks as historically small except as a possible beginning of modern barbarian invasions. After Rémy and his friends retreat to the countryside, they speak of their devotion to constantly evolving -isms. Rémy dies in the company of his friends and Sébastien, after a heroin injection from Nathalie, whom Rémy calls his guardian angel.
Denys Arcand, who wrote and directed the successful French Canadian film The Decline of the American Empire (1986), developed the idea of returning to the characters years later due to a fascination with death and an idea of having a character who is expecting to die. Part of his interest in the subject matter related to both of his parents dying of cancer. He had tried to write screenplays about non-Decline characters going to die for 20 years prior to The Barbarian Invasions, originally pitching the idea to the Canadian Broadcasting Corporation but having difficulty with the subject matter being overly sentimental. He finally decided to try the story with characters from The Decline of the American Empire because of his fondness for its cast members. There are also characters from Arcand's 1989 film Jesus of Montreal in the film.
The September 11 attacks of 2001 occurred when Arcand was nearly finished his screenplay, and gave new impetus to Arcand's ideas of "the decline of the American Empire." Arcand believed the attack represented the first of what would be many foreign attacks on the U.S. Arcand also referred to himself as "post-isms", and incorporated this discussion into the film.
Another statement he tried to make with his film was that heroin could be legalized for terminally ill patients in Canada, claiming it already is in England. Author Susan C. Boyd wrote that, despite what the film portrays, heroin has been legal in Canadian palliative care since 1984. To research how his character would find heroin, Arcand contacted the Royal Canadian Mounted Police and met with them in an interrogation room, resembling the one in the final film. He claimed the RCMP gave him the cellphone number of a Montreal detective, and when he called it, he heard shouting from a police raid on the Hells Angels, which resulted in the arrest of Maurice Boucher.
The film was produced by both Canadian and French companies, including Telefilm Canada, Société Radio-Canada and Canal+. The budget was $6 million budget.
The cast members from the previous film, including Dorothee Berryman, Louise Portal, Dominique Michel, Pierre Curzi and Yves Jacques, were easy to secure for the sequel. New to the cast was Marie-Josée Croze, who was selected by Arcand after starring in the Canadian films Maelstrom (2000) and Ararat (2002). She found Arcand allowed her freedom in how she interpreted her role. In The Decline of the American Empire, Croze's character Nathalie is played by child actress Ariane Frédérique.
Stéphane Rousseau, better known in Quebec as a stand-up comedian than an actor, was cast as Sébastien, after Dominique Michel urged Arcand to allow Rousseau to audition. Arcand explained he felt Rousseau had the "authority" the other actors who auditioned did not, though Rousseau was surprised to get the part as he felt his character was colder and more of an intellectual than he was. Rousseau's mother had died of cancer when he was a child, and he had fought with his father, later incorporating that experience into his performance.
The film was shot over 50 days, beginning in September 2002 and finishing in November. The bulk of the film was shot in Montreal, with some scenes filmed in London. Footage from the World Trade Center attack shot by a Quebec architect and acquired by Radio-Canada was also used.
For the hospital scenes, the cast and crew employed Lachine General Hospital, an unused former hospital in Lachine, Quebec. Cinematographer Guy Dufaux found these scenes difficult to make interesting and realistic at the same time, and decided on more lighting for later scenes when the film's mood brightens, while using fluorescent fixtures and reflecting the former hospital's green painting to shoot the early scenes. As with the first film, scenes were filmed near Lake Memphremagog. Most of the film was shot using a Steadicam.
News that Arcand was working on a sequel to his 1986 film was received with a skeptical and negative response from critics. The film was screened at the 2003 Cannes Film Festival in May, where it received a 22-minute standing ovation, with distribution to 30 countries assured by the time Arcand received his Best Screenplay award. It was afterwards selected to open the gala at the 2003 Toronto International Film Festival in September, and also opened the Vancouver International Film Festival that month. The film began playing in Quebec theatres in May and ran for months, with its Canadian distributor being Alliance Films. It opened across Canada on November 21.
After Cannes, rights were sold to Miramax for distribution of the film in the United States. It opened in New York and Los Angeles on November 21. In France, the film was available on 450 screens at one time, the most for a Quebec film ever.
The film's box office performance at Quebec theatres between its opening in May 2003 and the fall was considered good. By December, its initial release across Canada made $5.9 million.
In France, it grossed the equivalent of US$8 million. According to Box Office Mojo, the film finished its run on June 3, 2004 after grossing $8,544,975 in North America and $18,379,681 in other territories, for a worldwide total of $26,924,656. It was one of Arcand's biggest box office successes.
The Barbarian Invasions has received positive reviews from numerous critics. In Canada, Maclean's critic Brian D. Johnson called it not only satirical but "a moving elegy to a generation that defined modern Quebec and has seen its passions rendered obsolete". Liam Lacey wrote in The Globe and Mail that the film is "upbeat and wryly positive, or at least as much as you could expect from a film that condemns the Quebec hospital system and features a death by cancer as its central theme". The film drew general attention for its criticism of Quebec's health care system. Peter Howell wrote in The Toronto Star that "It's the depth of emotions Arcand summons for his characters, and the way this superb ensemble cast bring them so vividly to life, that make The Barbarian Invasions a film not just to see, but to welcome home".
Roger Ebert of the Chicago Sun Times gave the movie four stars and called it "a movie with brains, indignation, irony and idealism". A.O Scott of The New York Times wrote "what makes The Barbarian Invasions much more than a facile exercise in generational conflict is that Denys Arcand, who wrote and directed it, has a sense of history that is as acute as it is playful", adding "The rapprochement between Remy and Sebastien is beautiful to watch" and Marie-Josée Croze's "spooky, melancholy intensity darkens the mood of buoyant sentimentality". Entertainment Weekly's Owen Glieberman gave the film a B-, noting Rémy's hedonism. David Denby of The New Yorker gave credit to Stéphane Rousseau for "a fascinatingly minimal performance". Jonathan Romney of The Independent wrote "The film has its pros and cons, but you can't fault it for ambition: it not only muses on life and death, but also undertakes fairly comprehensive philosophical soundings of the way the world is today". Romney added Croze "has simply the most nuanced presence here: thoughtful, introspective, with a reassuring warmth and lack of cartoonishness". Peter Bradshaw, writing for The Guardian, disdained the movie, calling it "grotesquely overpraised", "shot through with middlebrow sophistication, boorish cynicism, unfunny satire, a dash of fatuous anti-Americanism and unthinkingly reactionary sexual politics". English Professor Peter Brunette wrote "its analysis of this state of affairs is all too often annoyingly rhetorical and, finally, altogether too facile".
In 2004, the Toronto International Film Festival ranked the film tenth in the Top 10 Canadian Films of All Time. David Lawrence Pike criticized the use of the World Trade Center footage as exploitative, but said despite "the crudeness and vulgarity", the film had a "particular brilliance". In January 2010, the review aggregator Rotten Tomatoes reported that 82% of critics gave the film positive reviews, based on 123 reviews. Metacritic reports that the film has an average score of 71 out of 100, based on 35 reviews.
The Barbarian Invasions is considered historically significant as the first Canadian film to win the Academy Award for Best Foreign Language Film. Canadian historian George Melnyk interpreted it as a sign that "Canadian cinema has come of global age", also pointing to Atanarjuat: The Fast Runner (2001) winning the Camera d'Or at Cannes.
Marie-Josée Croze's honour for Best Actress at the 2003 Cannes Film Festival was considered unlikely. She was not present to accept the award. The film's victory at France's national César Awards was also considered a surprise, since it is mainly a Quebec film. It received the most nominations at the 24th Genie Awards.