The heavyweight division, as defined by the unified rules of MMA via the Association of Boxing Commissions , consists of fighters who are between 206 and 265 pounds. Prior to the New Jersey State Athletic Control Board conceiving a set of rules and weight classes in 2000 that became the base of operations we are now familiar with today, MMA was essentially the Wild West when it started out in the 1990s. From open-weight matches to one-night tournaments, heavyweight fighters and classifications were a common occurrence in MMA’s early days. However, since the early 2000s, the heavyweight classification has largely stayed consistent across major promotions (despite some disarray amongst the lower weight classes).
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The 5 greatest heavyweight wars in MMA history, ranked – MMA Junkie