back when he ufc started out it wanted something to be like its catch phrase. like lets say the goldena arches for mcdonalds and so on. anyway the ufc chose to make the its ring in a shape as an octagon so it could always been remembered and its worked. . i read in a magazine, that martial arts had always been on a white man. or a ring. now when u think mma u think octagon. though this is good for the ufc, not all mma competitions use this. dana white said now the octagon is notorious for its marketing . like on ppv nights, the ultimate fighter, and commercials they wanted the octagon to be a center of attention like wow, look at it. and i think its worked. the octagon has now transformed mma fighting .