I'm looking for all of the administrative boundaries in your China Administrative map but I could not find the administrative boundary, for Chongqing.
Chongqing is not a province. Chongqing had been a MSA (city) within Sichuan province but was upgraded to one of the provincial level MSAs several years ago. That is why some maps list it as a province (similarly Washington DC is not a State but a State-level District).
Our 1990 Administrative Boundary data is before the upgrade.