The series is inspired by the tales of the Norsemen of early medieval Scandinavia. It broadly follows the exploits of the legendary Viking chieftain Ragnar Lothbrok and his crew, family and descendants, 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 the 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 Varangians. The series begins at the start of the Viking Age, marked by the Lindisfarne raid in 793.