Central Thailand is a region of Thailand, covering the broad alluvial plain of the Chao Phraya River. It
is separated from North-East Thailand (Isan) by the Phetchabun mountain range, and another mountain range separates it from Myanmar to the west. In the north it gently changes into the more hilly Northern Thailand. The area was the heartland of the Ayutthaya kingdom, and is still the dominant area of Thailand.
Central Thailand including the eastern provinces is divided into 26 provinces. Especially for statistical purposes these are divided into 4 groups 1 :
Bangkok and vicinity
, Nakhon Pathom, Nonthaburi, Pathum Thani, Samut Prakan, Samut Sakhon
Sub-central region: Ang Thong, Ayutthaya, Chainat, Lopburi, Saraburi, Singburi
n: Chachoengsao, Chanthaburi, Chonburi
, Nakhon Nayok, Rayong
, Prachinburi, Srakaeo, Trat
The eastern region is sometimes listed as a separate region destinct from central Thailand - sometimes only the four coastal provinces, sometimes the above list excluding Nakhon Nayok. None of these regions are actually administrative subdivision, they are only geographical or statistical groupings.