Pridnestrovian Moldavian Republic is a breakaway state from Moldavia with limited recognition, but for all intensive purposes functions as an independent state, including having its own currency and postage stamps. The stamps are only valid on local mail and mail to Russia. Other international mail must have Moldovan stamps.
For short, the official name is Pridnestrovie, but in English is commonly called PMR and Transnistria.
Location: Located mainly on a strip of land between the Dniester river and the internationally recognized eastern Moldovan border with Ukraine.
Capital: TiraspolPopulation: 518,000Historical Dates:1990 (spring): Popular front of Moldova wins first free parliamentary elections in the Moldavian Soviet Socialist Republic of the USSR.
1990 (Sept 2): Pridnestrovian Moldavian Soviet Socialist Republic was proclaimed as a Soviet republic by an ad hoc assembly, the Second Congress of the Peoples' Representatives of Transnistria, succeding from Moldavia SSR, with the end of the Soviet Union shortly after, this became complete Independence.
1990 (November): War breaks out between Moldavia and Pridnestrovie.
1991: (August 27): Moldova declares independence from the USSR.
1992: (June 30): First stamps issued by Pridnestrovie, overprinted USSR stamps.
1992: (July 21): Ceasefire signed between Moldavia and Pridnestrovie.
The first two stamps of PMR:


The overprints exist horizontal and vertical.
Local cover from the "Ministry of Industry"


I am not sure how the date is arranged, but I assume the date of the cancel is 22/04/2011, Tiraspol.