Oudong is a former town of the post-Angkorian period situated in present-day Phsar Daek Commune, Ponhea Lueu District, Kandal Province, …Oudong is a former town of the post-Angkorian period situated in present-day Phsar Daek Commune, Ponhea Lueu District, Kandal Province, Cambodia. Located at the foothill of the mountain Phnom Oudong, also known as Phnom Preah Reach Troap, about 35 km northwest of the modern capital Phnom Penh via National Road No. 5, Oudong was a royal residence and Cambodia's capital for almost 250 years until 1866. A monumental royal necropolis of sovereigns of several centuries is scattered on top of the prominent bisected mountain, which runs from the southeast to the northeast.