Polish-Lithuanian-Ruthenian Commonwealth
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
Polish-Lithuanian-Ruthenian Commonwealth (Polish: Rzeczpospolita Trojga Narodów, Commonwealth of Three Nations). The creation of a Duchy of Ruthenia was considered at various times, particularly during the 1648 Cossack insurrection against Polish rule in Ukraine. Such a Ruthenian duchy, as proposed in the 1658 Treaty of Hadiach, would have been a full-fledged member of the Polish-Lithuanian Commonwealth, which would thereby have become a tripartite Polish-Lithuanian-Ruthenian Commonwealth. But due to szlachta demands, Muscovite invasion, and divisions among the Cossacks, the plan was never implemented.