From tasteofcinema,.com:
"The 1950s are considered the Golden Age of Japanese cinema. The aftermath of World War II and particularly the atomic bomb, and the subsequent American occupation left the country scarred, but filled with inspiration and eagerness to start over.
As the Japanese economy started to rise once more, five major studios emerged that shaped Japanese cinema. Toho, Daiei, Shochiku, Nikkatsu, and Toei hired the most gifted artists of the era and financed their movies, in a tactic that resulted in a plethora of masterpieces. In the process, they also made a lot of money, as the people, having their pockets filled due to the rapid economical growth, filled the cinemas." (Read more on the website)