The Akizuki and Yamana clans existed in feudal Japan, though they reached their peaks centuries apart. The Hayakawa clan is fictional.
Akira Kurosawa made this commercial and accessible film as a way to repay Toho Studios for allowing him to make riskier, more artistic fare such as Rashomon (1950). It was later one of the greatest inspirations for George Lucas' La guerre des étoiles (1977), which originally started out as a sci-fi themed remake of this film set in the distant future, similar to how Les sept mercenaires (1960) was a Western-themed remake of Kurosawa's Les sept samouraïs (1954). However Star Wars went through so many drafts and rewrites that the final version of the film bears almost no resemblance to The Hidden Fortress. The inspiration can also be seen in Star Wars Épisode I: La menace fantôme (1999), which shares certain plot points with this film.
In an interview for the Criterion collection DVD, George Lucas stated that while this film is a story about a princess and her protectors that this was not the primary element that he employed in La guerre des étoiles (1977). He stated that he was more concerned with the way that Hidden Fortress is told through the eyes of two lesser characters. In Hidden Fortress it is the two thieves; in Star Wars it is C3PO and R2D2. In both films the comical interplay between the two characters is a major theme.
A bit distraught from the lack of success of his last two films which he deemed heavy and tragic, Akira Kurosawa took a new tone with this movie, stating, "I want to make a 100% entertainment film, full of thrills and fun".
Akira Kurosawa: [weather] The long rainy sequence where the farmer's daughter returns to her company's hideout.