Complex sentence: Phou Khao Khouay is a National Protected Area, a beautiful nature reserve, located 40 km northeast of Vientiane has large stretch of sandstone mountain range with sandstone cliffs, river gorges and three large rivers with tributaries debouches into the Mekong River.
Split into simpler sentences: Phou Khao Khouay is a National Protected Area, located 40 km northeast of Vientiane. It has a large stretch of mountain range with sandstone cliffs, river gorges and three large rivers with tributaries which flow into the Mekong River.