Vikings is inspired by the sagas of Viking Ragnar Lothbrok, one of the best-known legendary Norse heroes and notorious as the scourge of England and France. The show portrays Ragnar as a farmer who rises to fame by successful raids into England, and eventually becomes a Scandinavian king, with the support of his family and fellow warriors: his brother Rollo, his son Björn Ironside, and his wives—the shieldmaiden Lagertha and the princess Aslaug.
Vikings was renewed for a fourth season in March 2015 with an extended order of 20 episodes, which premiered on February 18, 2016. On March 17, 2016, History renewed Vikings for a fifth season of 20 episodes.
The series is inspired by the tales of the raiding, trading, and exploring Norsemen of early medieval Scandinavia. It follows the exploits of the legendary Viking chieftain Ragnar Lothbrok and his crew and family, as notably laid down in the 13th century sagas Ragnars saga Loðbrókar and Ragnarssona þáttr, as well as in Saxo Grammaticus‘s 12th century work Gesta Danorum. Norse legendary sagas were partially fictional tales based in Norse oral tradition, written down about 200 to 400 years after the events they describe. Further inspiration is taken from historical sources of the period, such as records of the Viking raid on Lindisfarne depicted in the second episode, or Ahmad ibn Fadlan‘s 10th-century account of the Volga Vikings. The series is set at the beginning of the Viking Age, marked by the Lindisfarne raid in 793.