There are different categories of ghosts. Certain ghosts dwelling in mountains and forests are generally known as Phi Khao () and Phi Pa (). Geographic locations such as the Phi Pan Nam Range (), 'the mountain range that the spirits use to divide the waters', and Phae Mueang Phi (แพะเมืองผี) are named after ancient ghosts believed to dwell in these places. Female ghosts or fairies related to trees such as Nang Ta-khian and Nang Tani are known generically as Nang Mai ( 'Lady of the Tree').