Altanbulag (Mongolian: Алтанбулаг, "golden spring") is a sum (district) of Selenge Province in northern Mongolia.

It is located about 25 km from the provincial capital of Sükhbaatar, on the border with Russia opposite the town of Kyakhta.

The southwestern quarter of town was occupied by "Bukharans" as the Russians called traders from Central Asia.

For some purposes the Dzarguchei dealt with the Tushetu Khan in Urga who was partly supervised by a Manchu resident.

; Маймачен in Russian), City of Buying and Selling in English) which derived from the Chinese name Mǎimàichéng.