The Boxer From Shantung (1972, Hong Kong). Director: Chang Cheh.
Some people might find the violence of this scene too prolonged and excessive. Some may find it laughable. But the scene must be understood in the context of the story. Contrary to stereotypes, this was not some cheap 'chop-socky' movie with non-stop fighting. Story-wise, this movie was highly influential on a number of later films, martial arts-related or otherwise. It has been said that this final fight scene was a possible influence on the final battle scene in Brian DePalma's Scarface (1983). Personally, other than both films' finales having an upper floor, a staircase, swarms of attackers and lots of blood, I've never seen much of a connection. I suppose only DePalma himself could answer that. There is little doubt that this movie's finale was one of Quentin Tarantino's inspirations for the large-scale fight scene in Kill Bill Vol. 1.
The choreography and execution of the fights were typical early '70s Hong Kong "basher" style, with little to no "stylishness" or "artistic grace" of later films. In other words, nothing "pretty" here. Sometimes the moves might appear awkward and even uncoordinated. This had to do with the choreography style of that period. Leading man Chen Kuan-Tai was a Southeast Asian full-contact fighting champion in 1969, so he wasn't some non-martial artist. In later films, his onscreen style was very smooth. But The Boxer From Shantung was arguably Chen Kuan-Tai at his most intense.
Finale, part 1: Chen Kuan-Tai vs Ku Feng, Wang Ching, Feng Yi, Chiang Nan, etc.
Finale, part 2: