China League One, also known as Chinese Jia League, is the second tier of Chinese clubs. Above League One is the Chinese Super League.
Prior to the formation of the Chinese Super League, Jia League was known as Jia B League. The then top two levels of Chinese football league were known as Jia A League and Jia B League respectively. Jia A was rebranded as CSL and Jia B was rebranded as the current Jia League in 2004. Below the Jia League is the Yi League, following the Chinese Heavenly Stems naming convention of numbers.
It is currently made up of 16 teams, playing each other home and away once. At the end of each season, the top two teams are promoted to the CSL and the two lowest placed teams from the CSL are relegated to China League One. The top two teams from China League Two are promoted and replace the two lowest placed teams from China League One.