One of beautiful sand dune in the Gobi is the Khongor Sand Dunes that extend more than 180 km (112 miles) with majestic heights of 15-30 m along the northern side of Sevrei and Zuulun mountain ranges. The largest dunes are northwest of the range up to 800 metres high The Khongor Sand Dunes are some of the largest and most impressive white sand dunes in Mongolia. The dunes make sound like plane engine in a windy day so it has been named as Singing Dunes.
From the top of the sand dunes, the view of the desert is awesome. The Khongoryn River flows along the sand dunes and gives birth to oases. The sand dune change the color with each hour of one day, from yellow to silver to rise colored at dawn / sundown. Picturesque Khongor Sand dunes against a sky of blue or a full moon, with perfectly contoured shadows of ripples and undulating crests, have always been a favorite subject of photographers. Depending upon one’s particular situation, sand dunes can be one of the most incredibly beautiful, thrilling, eerie, treacherous or just plain inhospitable places on earth.
Mongolia has three types of deserts, and some of it has enough grass for livestock to graze, but the Khongoryn Els, in the extreme south of the Gobi Desert, has a huge range of sand dunes – 6–12 kilometres (3.7–7.5 mi) wide, 100 kilometres (62 mi) long (180 kilometres (110 mi) is also mentioned) and rising to a height of 80 metres (260 ft) (a maximum height to the apex can be 300 metres (980 ft)). They are similar to the dunes of Egypt. The sands have attractive curves which end in a sharp edge, making wave like patterns on the sand. They continually change shape due to wind and reflect yellow-white colours as the intensity of light changes during the day.
As the sand is moved due to winds or is in the process of collapse due to small avalanches, a strong sound is made giving it the name Singing Sands. A French team has explained this phenomenon as due to a thin surface coating of slate over the sand grains which causes the sand to make a resonant sound. The sound is also attributed to heat, the weather conditions in the desert and to the avalanche effect caused by the sand particles moving harmoniously. This sound is also compared to the sound made by an aircraft during take-off and landing stages. Its length and width vary. The largest of these dunes is found in the northwestern end of the range.
The northern border of the dunes is skirted by a small river, the Khonggoryn Gol, where green pastures are noted. The river is sourced by subterranean flows from the mountains forming its valley. Grazing by camels and horses of the nomadic population of the area is noted. The wildlife recorded consist of Saker falcons, Pallas’s sandgrouse and Saxaul sparrow, Corsac fox or red fox.