From The Art and Popular Culture Encyclopedia
The most famous saga-genre is the Íslendingasögur (sagas concerning Icelanders), which feature Viking voyages, migration to Iceland, and feuds between Icelandic families. But sagas' subject matter is diverse, including pre-Christian Scandinavian legends; saints and bishops both from Scandinavia and elsewhere; Scandinavian kings and contemporary Icelandic politics; and chivalric romances either translated from Continental European languages or composed locally.
Sagas originated in the Middle Ages, but continued to be composed in the ensuing centuries. Whereas the dominant language of history-writing in medieval Europe was Latin, sagas were composed in the vernacular: Old Norse and its later descendants, primarily Icelandic.