Mel Brooks did not invent the comedy spoof movie, but his best work ("Blazing Saddles", "Young Frankenstein", "Dracula, Dead And Loving It", and "High Anxiety") certainly make the most of it - even if some of it gets rather too dirty (literally dirty - "caca" dirty). "History Of The World" is a funny film, but it is not one of his best films. It looks like it was based on bits and pieces of ideas that could have been built up into separate movies: a film about the stone age, a film about the Roman Empire, a film about the French Revolution. I am sure that Brooks was inventive enough to have created three film spoofs, but for some reason he decided to just concentrate on pasting these mini-spoofs together.
It has wonderful moments in it - some are thrown away. The four desperate refugees from the Roman Empire, followed by centurions, pray for a miracle. Suddenly they see an old man - Brooks dressed like Moses (from an earlier sequence in the film). A river is parted like the Red Sea with "Moses" arms in the air. The refugees flee thanking God and Moses. In a moment we see there is a robber in back of "Moses" holding him up (hence his arms in the air), and when the robber leaves the old man starts cursing him.
Similar stuff is throughout the film (typical of Brooks' inventiveness). After fleeing Rome, Brooks has reached Palestine and is the waiter serving the "Last Supper". Besides having a problem when he keeps saying "JEEZUS" causing John Hurt (who is Christ) to ask, "Yes?", there is the problem of the painting being done by Da Vinci (Art Metrano), and how Brooks manages to get into the background of the masterpiece - holding his tray like a halo behind Hurt).
Brooks uses a number of his regulars in the film: Madeline Kahn as the Empress Nympho, Dom DeLuis as the Emperor (one could call him "piggy" after one particular comment about his eating habits), Harvey Korman as the foppish Count du Monet, Sid Caesar as a caveman who is full of awe. He was also lucky to have Gregory Hines, usually a dancer but here a strikingly breezy comic, and Orson Welles doing the narration properly (note his voice's confusion at the start when describing the first heterosexual marriage, followed by the first homosexual one).
The disjointed style is a minor problem in enjoying the film. Judging from the final scenes from the sequel, Brooks could have done a Viking movie, a skating film about Nazism, and a space musical about the Jews. Alas, only those scenes were ever shot. A second part might not have been a great film either, but it would have been quite as amusing.