 The legendary Arthur developed as a figure of international interest largely through the popularity of Geoffrey of Monmouth's fanciful and imaginative 12th-century "Historia Regum Britanniae" ("History of the Kings of Britain").In some Welsh and Breton tales and poems that date from before this work, Arthur appears either as a great warrior defending Britain from human and supernatural enemies or as a magical figure of folklore, sometimes associated with the Welsh otherworld Annwn.How much of Geoffrey's "Historia" (completed in 1138) was adapted from such earlier sources, rather than invented by Geoffrey himself, is unknown.