The Varangians or Varyags is the name given by Greeks and East Slavs to Vikings, who between the 9th and the 11th centuries rule the medieval state of Rus', and form the Byzantine Varangian Guard.

According to the 12th century Kievan Primary Chronicle, a group of Varangians known as the Rus' settles in Novgorod in 862, under the leadership of Rurik.

Before Rurik, the Rus' might have ruled an earlier hypothetical polity.

Rurik's relative Oleg conquers Kiev in 882, and establishes the state of Kievan Rus', which is later ruled by Rurik's descendants.Engaging in trade, piracy and mercenary activities, Varangians roam the river systems and portages of Gardariki, as the areas north of the Black Sea are known in the Norse sagas.

They control the Volga trade route (the route from the Varangians to the Arabs), connecting the Baltic to the Caspian Sea, and the Dnieper trade route (the route from the Varangians to the Greeks) leading to the Black Sea and Constantinople.

These are the critically important trade links at that time, connecting Dark Age Europe with wealthy and developed Arab Caliphates and the Byzantine Empire; via these routes, most of the silver coinage comes from the East to the West.

Attracted by the riches of Constantinople, Rus' Varangians initiate a number of Rus'-Byzantine Wars, some of which result in advantageous trade treaties.

At least from the early 10th century, many Varangians serve as mercenaries in the Byzantine Army, comprising the elite Varangian Guard (the personal bodyguards of Byzantine Emperors).

Eventually most of them, both in Byzantium and in Eastern Europe, are converted from paganism into Orthodox Christianity, culminating in the 988 Christianization of Kievan Rus'.

Coinciding with the general decline of the Viking Age, the influx of Scandinavians to Rus' stops, and Varangians are gradually assimilated by East Slavs by the late 11th century.