Phetchabun (Thai: เพชรบูรณ์, pronounced [pʰét.tɕʰā.būːn]) is one of Thailand's seventy-six provinces (changwat) and lies in lower northern Thailand. Neighbouring provinces are (from north clockwise) Loei, Khon Kaen, Chaiyaphum, Lopburi, Nakhon Sawan, Phichit and Phitsanulok.
Nakhon Sawan province (Thai: จังหวัดนครสวรรค์, pronounced [ná(ʔ).kʰɔ̄ːn sā.wǎn], lit. 'Heavenly City') is one of Thailand's seventy-six provinces (changwat). It lies in lower northern Thailand, neighbouring the provinces of Kamphaeng Phet, Phichit, Phetchabun, Lopburi, Sing Buri, Chai Nat, Uthai Thani, and Tak (clockwise from north).