500 Tögrög Moscow-Ulaanbaatar-Beijing Railroad

The Moscow–Ulaanbaatar–Beijing rail corridor, a branch of the Trans-Siberian network, was completed through Mongolia in 1956 after years of Soviet-directed construction using Mongolian labor. The line cut the overland journey between the two capitals from weeks to days and fundamentally reoriented Mongolian trade away from caravan routes that had functioned for centuries.

The KM#101.1 designation distinguishes this from at least one variant — likely a difference in edge treatment or finish — suggesting the issue was produced in more than one version for the collector market.