Rattanak Kiri is the mountainous northeastern frontier province of Cambodia that borders Laos to the north, Vietnam to the east, Mondul Kiri Province to the south, and Stung Treng Province to the west.  It extends from the mountains of the Annamite Range in the north, across a plateau between the Tonle San and Tonle Srepok rivers. Famed for its stunning natural beauty and ethnic diversity, Rattanak Kiri is full of natural and cultural treasures just waiting to be discovered. Its capital is Banlung City.

Rattanak Kiri boasts some of the most striking landscapes the region has to offer and is home to several settlements of ethic hill tribes. Among the many picturesque natural sites are the crystal clear Yeak Laom volcanic lake, incredible fresh waterfalls, gem mines, and a dense rainformest teeming with exotic flora and fauna. In contrast to modern day opulence, this province remains largely untouched as the majority of the population in Rattanak Kiri is made up of ethnic minority groups living harmoniously with nature.

References:
http://www.tourismcambodia.org