The country of Mongolia is divided into 21 provinces (, aimag) and the capital (ýøùÃÂûÃÂû, niislel) Ulaanbaatar.
Secondary subdivisions outside Ulaanbaatar are called "sum" (ÃÂÃÂü, often transcribed as soum). In 2006, Mongolia had 331 sums. Sums are further subdivided into bags (ñðó). While sums always have a permanent settlement as administrative center, many bags do not.
Ulaanbaatar is divided into nine düüregs (ôïïÃÂÃÂó, usually translated as district), which are further subdivided into khoroos (àþÃÂþþ, most often translated as subdistrict, microdistrict or simply district), which are further subdivided into khesegs (most often translated as neighborhood).
Officially, Mongolia is divided into 4 administrative tiers, with different types of administrative unit on each tier: