The NWA World Welterweight Championship was nominally a Mexico based championship, having actually been created before the formation of the NWA (and EMLL joining the NWA.) Due to legal threats from the NWA, CMLL stopped using those initials in association with this championship in 2010, referring to it only as "World Welterweight Championship".
The championship appeared to be forgotten after it was vacated in 1992. Misterioso was the champion of the time, by left in the mass exodus to AAA. CMLL had recently created it's own CMLL World Welterweight Championship in 1992 and had be considering merging the two championships. Instead, they just allowed this championship to stay empty.
Three years later, Negro Casas won a match for the vacant championship over El Hijo del Santo, as part of their infinite rivalry. However, CMLL was still not intending to use the belt; Negro won the belt to provide another champion for the J-Crown Octuple Junior Tournament and Championship. The championship changed many times as part of the tournament and the length of the championship.
After the J-Crown broke up, the championship ended up as a possession of various Ultimo Dragon promotions and off-shoots. It was widely reported Dragon purchased the NWA World Middleweight Championship from CMLL around this period, so the same may be true with this title. This belt was used as part of Ultimo Dragon's Toryumon promotion during it's early years, until it was ultimately replaced by the promotion's own championships.
When this championship was dropped for Toryumon, it disappeared for three years before resurfacing in as part of Ultimo Dragon's personal shows in Mexico. Hajime Ohara won the vacant championship, defeating the reigning Mexican National Welterweight championLa Mascara. Ohara continued defending the championship on Dragon's occasional shows in Mexico and Japan. He wrestled as a rudo in Mexico, but was obviously Dragon's protege and top remaining student.
Ohara briefly lost this championship to Super Delfin and won it back, mostly unnoticed by the lucha libre audience. While the championship was mentioned in Ohara's CMLL matches (usually second or third on the card), it was treated as a title belonging to Ultimo Dragon's Dragon Gym shows, and not used for any CMLL feuds or rivalries.
This status quo came to an end in November of 2007. Ohara was suddenly in the semimain matches and feuding with (and losing to) La Sombra. After two weeks of trios matches, Sombra was given a title shot and won the championship. At age 18, La Sombra is believed to have become the youngest NWA World Champion of all time. It's also an indication CMLL received ownership of the belt back from Ultimo Dragon. Both Dragon and Ohara have disappeared from CMLL lineups, and the championship has stayed with CMLL.
As typical with CMLL based championships in this period, the champion had short feuds to set up title defenses, but no long term challenger to fend off. Sombra's match against Ephesto at the close of December was one of the best bouts of the year, but that match was set up with just a couple weeks of build. Still, this championship helped distinguish Sombra from the many other high flying tecnicos of similar level. Sombra's reign marked him as an upcoming top star, much like Mistico's first NWA World Middleweight Championship run did for him.
Mephisto's championship win came as a surprise. The title match was a special attraction for CMLL's return to running regular shows in Arena Coliseo Acapulco, and there was no hint of a pending change. After, it became clear the change was motivated by the upcoming debut CMLL Universal Tournament; CMLL had 15 eligible champions. Sombra still had half of the CMLL World Tag Team Championship, so Mephisto winning created a 16th champion to fill out the tournament. However, Mephisto was obviously over the weight limit for welterweight. While weight limits had long been ignored, this championship reign was an especially egregious case.
On August 12, 2010, CMLL announced a change with the NWA group of championships. The current physical title belts were all retired, replaced by newly belts with a different design. The old belts are now part of CMLL's mobile museum, though copies of them have turned up elsewhere. CMLL referred to the new championships as the CMLL Historic Championships and said the former NWA champions would be the first champions of the new belts. Outside not getting the physical belt back, that appeared to satisfy the NWA's complaints about using their trademarks. However, within weeks of that press conference, CMLL changed course. The championships were referred to as NWA World Historic Championships.
As part of the Lucha Future June 2011 tour of England, Blue Demon Jr. held a singles match between Casandro and Dr. Cerebro to decide his version of this title.
championship vacated on 2004.06.20 to focus on winning the Ultimo Dragon Gym championship; wrestlers leave to form the Dragon Gate promotion (replacing this title with the Open the Brave Gate championship) and this title remains with Ultimo Dragon
decision match on a Toryumon Mexico show for vacant championship
championship matches which were announced, but results were not found
Sources:
↑SuperLuchas - Guerrero won the match, but was DQed by the commission for using a punch. The referee was also suspended for missing it. Guerrero, EMLL and the NWA protested the decision and a rematch was held three weeks later.