RUs

Rus, also known as Rus’ or Rus, denotes the medieval East Slavic polity and the people who inhabited much of what is now Russia, Ukraine, and Belarus. The name is attested from the 9th century and is associated with a ruling elite of Varangian origin that formed in the eastern Baltic region and along the Dnieper, though the exact origin remains debated. Some scholars link the term to the Rus’ rulers who governed early towns, others to a river-based toponym.

Kievan Rus’ formed as a loose federation of East Slavic principalities under the rule of the Rurikid dynasty, with Kiev and Novgorod as prominent centers. The polity expanded during the 10th and 11th centuries, embracing large parts of present-day Ukraine, Belarus, and Russia. Christianity was adopted in 988 under Grand Prince Vladimir the Great, which helped integrate elites and trade with Byzantium. The legal framework developed through the Russkaya Pravda and other codes. By the 12th century, regional primacies and inter-principal strife weakened central authority.

In the 13th century, the Mongol invasion and the ensuing period of fragmentation left Kievan Rus’ as a collection of smaller principalities, notably Moscow, which rose in influence and eventually became the core of the Grand Duchy of Moscow and later the Tsardom of Russia.

The legacy of Rus’ is central to the cultural and linguistic history of East Slavic peoples; it is viewed as a predecessor of modern Russia, Ukraine, and Belarus. The term also entered Latin and Western historiography as Ruthenia, and in later periods referred to broader lands east of the Baltic.