Vikings are inspired by the stories of invasions, trade and exploration by the Norse in medieval Scandinavia. The series follows the explorations of the legendary Viking leader Ragnar Lothbrok and his crew and family, as was notably established in the 13th century Ragnars saga Loðbrókar and Ragnarssona þáttr, as well as in the 12th century Grammatic Saxon work, Gesta Danorum. The legendary Nordic sagas were partially fictional tales based on Nordic oral tradition, written about 200 to 400 years after the events they describe.
More inspirations are drawn from historical sources of the time, such as the records of the Viking attack in Lindisfarne, portrayed in the second episode, or Amade ibne Fadalane's account of the 10th century Volga Vikings. The series takes place at the beginning of the Viking era, marked by Lindisfarne's attack in 793.