The story
The promotion was founded in March 1997 as a successor to the UWF International, which closed down on December 1996. Kingdom featured much of UWF International's former roster and continued its shoot-style wrestling format, while incorporating elements of mixed martial arts (MMA) into its presentation.
The former Ace of the UWFi, Nobuhiko Takada, joined Kingdom only for a single match in their innaugural show Kingdom Birth Step 1 on May 1997 against Ryuki Ueyama, ending in a draw. Afterwards, Takada didn't continue on Kingdom and went to focus on his match against Rickson Gracie, scheduled for October 11 of that year.
The Ultimate Fighting Championship (UFC), at the time with financial issues, attempted to expand into the Japanese market by partnering with Kingdom. The resulting event was UFC Japan: Ultimate Japan. Hiromitsu Kanehara and Yoji Anjo signed to represent Kingdom in the tournament, but Kanehara injured himself in training and Kazushi Sakuraba was sent as a substitute. Lying about his weight (resulting in 60 lb of difference), he fought Brazilian jiu-jitsu black belt Marcus "Conan" Silveira twice and defeated him with an arm bar, this victory propelled Sakuraba's fame and would lead him to become a mainstay at PRIDE.
Kingdom's popularity did not reach or surpass that of the UWF International. Attempts to rectify this by using talent from other shoot-style promotions including Battlarts did little to help, and it seemed that in the eyes of the Japanese fans the era of shoot style wrestling had ended. As a result, Kingdom would go out of business in March 1998.
In the aftermath, Matsui, Sakuraba, Sano and Takada focused on competing for mixed martial arts promotion PRIDE as part of the Takada Dojo camp. Yamamoto and Kanehara jumped to Fighting Network Rings, which had been a splinter promotion formed from the UWF much like UWF International had been. Meanwhile, Kakihara and Takayama joined All Japan Pro Wrestling as free agents, while Anjo dabbled in K-1 before later reappearing in All Japan Pro Wrestling and Dream Stage Entertainment's Hustle as "Commander Anjoe".
A former trainee of the Kingdom dojo, Hidetada Irie, who debuted at Kingdom's final event, formed a successor promotion called "Kingdom Ehrgeiz", with himself as the top star. The promotion still exists, however, is very obscure and only promotes cards periodically.
From Wikipedia’s article on Kingdom Professional Wrestling, shared under CC BY-SA 4.0.4