In 2006, the first season, ten clubs played each other twice, with promotion going to the championship winner Chula-Sinthana FC.

The league was again split from two groups into five groups covering the North of Thailand, North East (Isan) region, Central East Zone, Bangkok central zone and South of Thailand.

Five group winners would enter a championship round to determine which three teams would gain promotion to the Thai Division 1 League.

The four promoted teams would be decided by two mini leagues at the conclusion of the regular season.

The sides coming in third and fourth position in the mini leagues would again play playoff matches against the bottom four clubs of Division 1 in order to gain promotion.

[4][5] The top two sides at the end of the 2008 season from A & B will be promoted to Thai Division 1 League.

The league winner of the five groups (North-east, Northern, Central & East, Bangkok Metropolitan, Southern) entered a final round group, Regional League Championships 2009, played on a home and away basis.

The top three teams of this championship group will achieve promotion to Thai Division 1 League.

From here, the top two teams from two groups of five would be promoted, the teams finishing in third and fourth place would enter another round of playoffs with the bottom four clubs of the 2010 Thai Division 1 League to determine if any more clubs would be promoted.