Cyprian, an educated Hesychastic-oriented monk, was one of the most important representatives of the Orthodox church in medieval Eastern Europe. All of the measures which he carried out during his time as the Metropolitan of Kiev were aimed at maintaining the unity of the metropolis, covering the whole of Eastern Europe, regardless of political divisions. He used proposals for negotiating a church union to find a solution to the situation which had arisen after the foundation of the Polish-Lithuanian union, which presented the Orthodox church with a new situation. He continued the reforms to the monasteries in the Grand Duchy of Moscow, which helped create the conditions for the development of the Russian autocephalous church. After a critical period in the 1380s, he contributed towards the restoration of the authority of the Russian metropolis and the entire ecclesiastical hierarchy.
The aim of the article is to analyze the widely spread idea that the late medieval Grand Duchy of Lithuania could unite the whole Rus' and pose an alternative to Moscow. It is shown that the Lithuanian rulers didn't lay such claims; the attempts to detect them in their statements made in 1358 and (allegedly) in 1399 are nothing but misinterpretations. It is also shown that Algirdas, Jogaila and Vytautas had no real chances to subjugate the Duchy of Moscow and its allies and vassals, both as the result of their military expeditions (1368–1372, 1406–1408) and due to the matrimonial union (1383/84).