Charicific Valley is a location in the Pokémon anime series which is located just outside of Violet City. The Charicific Valley is a training facility for Charizards. The only known human who lives in the valley is Liza, who, along with her Charizard, Charla, protects the valley from intruders.
Ash left his Charizard at the Charicific Valley to train while he was travelling. Noticing how much his Charizard enjoyed spending time in the valley, Ash left it in the Charicific Valley to train. Since Charizard has been in training, it has become very powerful, learning many new attacks including Dragon Breath, Overheat and Steel Wing.