Kampiew Sijantuek (nicknamed Piew) was born in the Thung Kratat Phatthana subdistrict of Nong Ki district in Buriram province on 4 February 1973.

At first, Sijantuek would watch Namphon train at the Nongkeepahuyuth gym which was famed for producing fighters that excelled in knee striking[1]: 1:32:55–1:34:56  as well as using select Muay boran techniques in real fights.

Namphon later pressured him to participate in a Muay Thai fight despite the fact that he did not have formal training, resulting in a draw and an 80 baht purse directly from the audience.

[3][4][5] Despite not wanting to fight, Sijantuek officially joined the Nongkeepahuyuth gym[5] to train under Hoymook and Poot Akkarat as he was pressured to take on more opponents.

Namphon would become a popular fighter in the Isaan region and eventually ran out of opponents, prompting him to begin fighting in Bangkok.

Under the advice of the Onesongchai promotion, Pramot Hoymook had Namkabuan temporarily train in the Muangsurin gym for 1 week[6] to further hone his skills for Lumpinee Stadium matchups.

[3] In 1989, once he was considered famous in the Kingdom of Thailand, Namkabuan's level of competition would continue to grow as he was matched up against Hippy Singmanee, Kraiwannoi Sit Kru Od, Karuhat Sor.Supawan, etc.

[2] In the 1990s, Namkabuan's fighting style was considered to be visually pleasing by the Thai audiences which resulted in his nickname of "The Ring Genius" as well as becoming one of the most well-known fighters in Thailand alongside Namphon.

[13][7]: 14:32, 18:17  Namkabuan also fought against Ramon Dekkers twice, losing the first time and winning their second fight in Morocco for the La Nuit des Titans promotion.

After defending it against "The Batman" Samkor Kiatmontep in December 1996, the Lumpinee Stadium officials could not find a challenger for Namkabuan in the following 6 months and forced him to give up the title.

Rainbow collided with the edge of the ring and the concrete floor, breaking his neck and putting him out of competition for months.

Namkabuan's daughters were initially unaware he was a famous Muay Thai fighter and had to be informed about his past by one of their PE teachers.