Principality of Pskov (Псковское княжество) was a small independent country (principality) on the south shore of Lake Pskov. Pskov at the southern end of the Peipus-Pskov Lake system at the southeast corner of Ugandi, about 150 miles (240 km.) southwest of Nevanlinna, and 100 miles (160 km.) west-southwest of Great Novgorod. Originally Pleskov, now the modern center of Pskov Oblast of Russia. It was a principality 862–1230s and then joined to Novgorod Republic. Pleskov was ruled by separate princes, but often it was ruled directly from Novgorod until the mid 13th century when the city began accepting as rulers princes exiled from their possessions. Each exiled prince that went to Pleskov could be proclaimed prince there (if principal throne wasn't occupied by other prince) but in any case he could get honorary reception and live there without fear for his life. From 1348 Pleskov became again independent from Novgorod and established again the Principality of Pskov, which was an aristocratic oligarchy, commonly called the Pskov Republic. False Dmitry III, supposed to have been a deacon called Sidorka, appeared suddenly, from behind the river Narova, in the Ingrian town of Iivananlinna, and proclaiming himself the tsarevich Dmitry Ivanovich on March 28, 1611. The Cossacks, ravaging the environs of Moscow, acknowledged him as tsar on March 2, 1612, and under threat of vengeance in case of non-compliance, the gentry of Pskov also kissed the cross (i.e., swore allegiance) to the Brigand of Pskov, as he was usually nicknamed. Finally, on May 18, 1612 he fled from Pskov.