Despite the stature of the cast and a respectable box office performance, the film was a critical flop; it is often ranked as one of the worst films of the 1950s and one of the worst ever. Wayne, who was at the height of his career, had lobbied for the role after reading the script and was widely believed to have been grossly miscast. The Conqueror was listed in the 1978 book The Fifty Worst Films of All Time. Wayne was posthumously named a "winner" of a Golden Turkey Award for his performance in the film.
Mongol chief Temujin (later to be known as Genghis Khan) falls for Bortai, the daughter of the Tartar leader, and steals her away, precipitating war. Bortai spurns Temujin and is taken back in a raid. Temujin is later captured. Bortai falls in love with him and helps him escape. Temujin suspects he was betrayed by a fellow Mongol and sets out to find the traitor and to overcome the Tartars.
The Conqueror received an A classification from the British Board of Film Censors but also required cuts to obtain the rating. The film premiered on February 2, 1956 in London before its Los Angeles premiere on February 22 and official theatrical release on March 28.
After Universal purchased the film rights in 1979, the studio released the film on DVD as part of their Vault Series on June 12, 2012.
The film is listed in Golden Raspberry Award founder John Wilson's book The Official Razzie Movie Guide as one of the 100 Most Enjoyably Bad Movies Ever Made.
Despite the film's reputation as a flop, it was the eleventh most successful film at the North American box office in 1956, earning $4.5 million.
The exterior scenes were shot near St. George, Utah, 137 miles (220 km) downwind of the United States government's Nevada National Security Site. In 1953, 11 above-ground nuclear weapons tests occurred at the site as part of Operation Upshot–Knothole. The cast and crew spent many difficult weeks at the site, and Hughes later shipped 60 tons of dirt back to Hollywood in order to match the Utah terrain and lend realism to studio re-shoots. The filmmakers knew about the nuclear tests but the federal government assured residents that the tests caused no hazard to public health.
Director Powell died of cancer in January 1963, seven years after the film's release. Armendáriz was diagnosed with kidney cancer in 1960, and killed himself in June 1963 after he learned his condition had become terminal. Hayward, Wayne, and Moorehead all died of cancer in the 1970s. Hoyt died of lung cancer in 1991. Skeptics point to other factors such as the wide use of tobacco – Wayne and Moorehead in particular were heavy smokers, and Wayne himself believed his lung cancer to have been a result of his six-packs-a-day cigarette habit. The cast and crew totaled 220 people. By the end of 1980, as ascertained by People magazine, 91 of them had developed some form of cancer and 46 had died of the disease. Several of Wayne and Hayward's relatives who visited the set also had cancer scares. Michael Wayne developed skin cancer, his brother Patrick had a benign tumor removed from his breast, and Hayward's son Tim Barker had a benign tumor removed from his mouth.
Reportedly, Hughes felt guilty about his decisions regarding the film's production, particularly over the decision to film at a hazardous site. He bought every print of the film for $12 million and kept it out of circulation for many years until Universal Pictures purchased the film from his estate in 1979. The Conqueror, along with Ice Station Zebra, is said to be one of the films Hughes watched endlessly during his last years.
Dr. Robert Pendleton, then a professor of biology at the University of Utah, is reported to have stated in 1980, "With these numbers, this case could qualify as an epidemic. The connection between fallout radiation and cancer in individual cases has been practically impossible to prove conclusively. But in a group this size you'd expect only 30-some cancers to develop. With 91 cancer cases, I think the tie-in to their exposure on the set of The Conqueror would hold up in a court of law." Several cast and crew members, as well as relatives of those who died, considered suing the government for negligence, claiming it knew more about the hazards in the area than it let on. Statistically, however, the odds of developing cancer for men in the U.S. population are 43% and the odds of dying of cancer are 23% (slightly lower in women at 38% and 19%, respectively).
Since the primary cast and crew numbered about 220, and a considerable number of cancer cases would be expected, controversy exists as to whether the actual results are attributable to radiation at the nearby nuclear weapons test site.Dell Four Color #690 (April 1956)