Regions in Cambodia

The Kingdom of Cambodia is a Southeast Asian nation bordered by Vietnam to the east, Laos to the north, Thailand to the northwest, and the Gulf of Thailand to the southwest. Cambodia has had a pretty bad run of luck for the last half-millennium or so.

Cardamom and Elephant Mountains (Battambang, Kampot, Koh Kong, Pursat, Sihanoukville, Sisophon, Bokor National Park, Kep)
the western mountain ranges, gulf coast beaches and offshore islands

North-western Cambodia (Angkor Archaeological Park, Siem Reap, Koh Ker, Poipet, Tonle Sap Lake, Preah Vihear)
Angkor, the main reason most visitors come to Cambodia, plus a huge lake and the northern mountains

Mekong Lowlands and Central Plains (Phnom Penh, Kampong Cham , Kompong Thom, Krek)
the capital city and the central flatlands

Eastern Cambodia (Banlung, Kratie, Sen Monorom, Stung Treng)
remote rural areas and national parks east of the mighty Mekong