Why is a square boxing area called a ring?

Well i never thought about it before, but come to think of it, yeah why is it called a ring, when in fact its shape is a square. Well I happened to read an issue regarding about this one.

The answer is that "ring" was first applied to to the boxing area but to the spectators who formed a ring around the combatants, according Brewer's Dictionary of Phrase and Fable. Although hand to hand combat was probably invented by the first 2 year old boy to discover he had a younger sibling, the first public matches took place in early 18th century England. These were bare-knuckled affairs with no time limit, no ropes and no referees. The winner was the last man standing. The ring of bloodthirsty fans formed an enclosure for the pugilist.

Although sanctioning bodies mandate the size of boxing rings, professional wrestling has no such requirement. In many venues, the same ring are used for boxing and wrestling. Amateur wrestling is done on mats laid across a floor. Ironically, the action in amateur wrestling is demarcated by a circle, yet it isn't called a ring. That's probably why the most common slang term for the ring in professional wrestling is "the squared circle".