One Rus

One Rus, also sometimes rendered as "United Rus'", "Whole Rus'", or "All Rus'", is a pan-nationalist and irredentist concept asserting that Ukrainians, Belarusians, and Russians constitute a single, unified nation or people stemming from a common historical and cultural origin in the medieval state of Kyivan Rus'.

The concept emphasizes shared ancestry, language similarities (particularly the East Slavic language family), Orthodox Christian faith, and cultural traditions to argue for the fundamental unity of the three Eastern Slavic nations. Proponents of One Rus' often minimize or deny the distinct national identities and cultural developments that have occurred in Ukraine and Belarus since the fall of Kyivan Rus'. They might describe Ukrainian and Belarusian languages as dialects of Russian, or view their cultures as regional variations within a broader Russian civilization.

Historically, the idea of One Rus' has been used to justify Russian political and cultural dominance over Ukraine and Belarus. During the Russian Empire and the Soviet Union, the concept served as a tool for Russification policies aimed at assimilating Ukrainians and Belarusians into a unified Russian identity.

In contemporary politics, the notion of One Rus' continues to be invoked by some Russian political actors and ideologues to support claims of historical right over Ukrainian and Belarusian territories and to justify interference in their internal affairs. The concept is often intertwined with notions of a "Russian world" (Russkiy mir), a sphere of influence based on shared Russian language and culture.

The concept of One Rus' is highly controversial, particularly in Ukraine and Belarus, where it is largely viewed as a form of Russian imperialism that undermines their sovereignty and denies their distinct national identities. Many Ukrainians and Belarusians strongly reject the idea, emphasizing their independent historical trajectories, cultural distinctiveness, and sovereign right to self-determination. Historians and linguists in these countries have extensively documented the unique development of Ukrainian and Belarusian languages, cultures, and national identities, challenging the assertions of a single, unified Rus' people.