The Bayan-Ölgii aimag (Mongolian: Баян-Өлгий Аймаг)(Alternately spelled Olgiy, Ulgii, etc. . .) is one of the 21 Aimags (provinces) of Mongolia. The Bayan-Ölgii aimag was established in 1940. Its capital is Ulgii city.

Geography
Bayan-Ulgii is Mongolia ‘s “Roof of the World”, a remote land of high mountains, even glaciers, steep slopes and rushing torrents. It is the western most aimag in Mongolia. It is very different than the rest of the country however. . Thus the speech, religion, and customs of the people are very different. Bayan Ulgii covers an area of 45,700 square kilometers.

Population
Unlike the rest of Mongolia the main population in this aimag is Kazakh. (88.7%). Smaller parts of the population are composed of Uriankhai (7.2%), Dörvöd (1.5%), Khalkha, Tuva and Khoshuud. A significant portion of the population speaks Kazakh language(Қазақ тілі) as their mother tongue and the Mongolian language only as a second language, if at all.
After democratization, many inhabitants moved to their historical homeland, Kazakhstan, assuming they would find a better future there. The result was a noticeable loss of population in 1991-1993, when approx. 30,000 were repatriated to Kazakhstan.
1956
census |
1960
est. |
1963
census |
1969
census |
1975
est. |
1979
census |
1981
est. |
1985
est. |
1989
census |
1991
est. |
1993
est. |
1995
est. |
1998
est. |
2000
census |
2002
est. |
2004
est. |
2005
est. |
| 38,800 |
44,600 |
47,800 |
58,100 |
66,600 |
71,400 |
74,500 |
82,400 |
90,900 |
102,817 |
75,043 |
82,259 |
87,341 |
94,094 |
98,066 |
99,112 |
95,758 |
Administrative subdivisions
Bayan-Ulgii has 12 sub administrative divisions which are called “sum”.
| Sum |
Mongolian |
Sum population (1985)[7] |
Sum population (1994)[8] |
Sum population (2005)[3] |
Sum centre population (2005)[3] |
Area (km²)[7] |
Density (/km²) |
| Altai |
Алтай |
3,400 |
3,237 |
3,914 |
977 |
3,200 |
1.22 |
| Altantsögts |
Алтанцөгц |
3,300 |
3,038 |
3,038 |
1,302 |
1,800 |
1.69 |
| Bayannuur |
Баяннуур |
4,800 |
4,507 |
5,320 |
2,005 |
2,300 |
2.31 |
| Bugat |
Бугат |
3,300 |
2,777 |
3,604 |
1,109 |
2,000 |
1.80 |
| Bulgan |
Булган |
5,000 |
5,115 |
5,901 |
1,298 |
5,000 |
1.18 |
| Buyant |
Буянт |
2,300 |
2,546 |
3,002 |
722 |
1,800 |
1.67 |
| Delüün |
Дэлүүн |
6,600 |
6,782 |
8,183 |
1,507 |
5,600 |
1.46 |
| Nogoonnuur |
Ногооннуур |
7,500 * |
6,331 |
6,539 |
2,160 |
5,300 * |
1.52 * |
| Ölgii (city) |
Өлгий |
24,000 |
21,569 |
28,248 |
27,568 |
100 |
282.48 |
| Sagsai |
Сагсай |
4,100 |
3,746 |
5,185 |
1,235 |
3,100 |
1.67 |
| Tolbo |
Толбо |
4,100 |
3,746 |
4,260 |
986 |
3,000 |
1.42 |
| Tsagaannuur |
Цагааннуур |
- |
1,878 |
1,528 |
1,270 |
- |
- |
| Tsengel |
Цэнгэл |
6,700 |
6,539 |
8,364 |
1,597 |
6,500 |
1.29 |
| Ulaankhus |
Улаанхус |
7,300 |
6,807 |
8,672 |
1,304 |
6,000 |
1.45 |
Transportation
By air
The Ölgii Airport (ULG/ZMUL) has one unpaved runway. It offers regular flights to Ulan Bator and irregular flights to Almaty in Kazakhstan.
There are MIAT(Mongolian Airlines),Eznis and Aero Mongolia that offers local flights. Currently, Eznis is offering flights between Ulgii and Ulaanbaatar.
By land
A road connecting to Russia starts in Tsagaannuur sun. The border with China is open for some periods of year. People can come to Bayan-Ulgii by passing Russia or Kazakhstan if they want to come from Europe.
Also to the 21 subdivisions of Ulgii, the only means of transportation is by jeep.
Communication
Almost every home have installed local phones. Mongolian code is +976. Bayan-Ulgii code is +01422. There are two main mobile operators. Main mobile operator is MobileCom Co,..Ltd. MobileCom serves services based on GSM system. So, if your country has the sam system you can bring your mobile phone and can be used in Ulgii.
Another one is Skytel Co,..Ltd. System of Skytel is based on CDMA system.