Curious + Wrong Presumption...
In the preamble of the film, Director/Producer Rex Ingram states that due too 'commercialism' the Public does not want costume/period pictures. Allegedly because they are not popular. Question, was Mr. Ingram just trying to justify a cheap way to make the movie or he was he divorced from reality?
Just the previous year THE MARK OF ZORRO (1920) was a tremendous success. The same year of THE CONQUERING POWER (1921) Douglas Fairbanks brought out the even more popular THE THREE MUSKETEERS (1921). He would continue to release such pictures too success for the rest of the decade. The most popular picture of the previous era BIRTH OF A NATION (1915) was set in the Civil War, seems there were a-lot of costumes there!
You wonder how much of what he stated he really believed in. After all the next year Mr. Ingram produced THE PRISONER OF ZENDA (1922). Ruritania was certainly not a 20th Century Modern State!