narrative poetry ("romance") usually written in octosyllabic rhymed couplets and telling stories of chivalry and love. The most famous "romans" are those of the "Matter of Britain" dealing with Arthurian romance, the stories of Tristan and Iseult, the heroic legend of the doomed utopia of Camelot and the Holy Grail. Much of this material derives from Breton (Celtic) legends. The most important of these writers was Chrétien de Troyes (twelfth century). The "Matter of Rome" concerns romances that take place in the ancient world, such as romances dealing with Alexander the Great, Troy, the Aeneid and Oedipus. Yet Bodel's category leaves little place for another important group of romances: those adventurous romances which are often set in Byzantium. Sometimes linked with the "roman" are the Breton lais, narrative ballads of Britain by Marie de France, many of which have Celtic themes and origins. Around a hundred verse romances survive from the period 1150–1220. From around 1200 on, the tendency was increasingly to write the romances in prose (many of the earlier verse romances were adapted into prose versions), although new verse romances continued to be written to the end of the 14th century., and it was chiefly in their prose form that many romances were read from the 14th to the 16th century. The success of the early Arthurian romances also led, from around 1200 on, to a restructuring and compiling of the material into vast prose cycles. Important "Matter of Rome" romances of the 12th century Roman de Thèbes Roman d'Enéas (1160) Roman de Troie (1154–1173) – Benoît de Sainte-Maure Roman d'Alexandre (1177) – this romance uses a twelve-syllable verse and is the reason why this verse length is termed alexandrine Important Byzantine and adventure romances of the 12th century Flore and Blanchefleur Florimont – Aimon de Varenne (1188) Guillaume d'Angleterre – sometimes ascribed to Chrétien de Troyes Robert le Diable Important romances of Britain of the 12th and 13th centuries Brut – Wace Erec and Enide – Chrétien de Troyes Cligès – Chrétien de Troyes (1162) Lancelot" or "Lancelot, the Knight of the Cart – Chrétien de Troyes (1164) Yvain, the Knight of the Lion – Chrétien de Troyes (1180) Perceval or the Story of the Grail – Chrétien de Troyes (1185) Romance of the Grail – Robert de Boron (1191–1201) Tristan – Thomas of Britain (1155–1178) Tristan – Béroul (c.1190) Roman de Fergus – William the Clerk