 For example, 60 manuscripts are extant containing the "Brut y Brenhinedd", Welsh-language versions of the "Historia", the earliest of which were created in the 13th century.The old notion that some of these Welsh versions actually underlie Geoffrey's "Historia", advanced by antiquarians such as the 18th-century Lewis Morris, has long since been discounted in academic circles.As a result of this popularity, Geoffrey's "Historia Regum Britanniae" was enormously influential on the later medieval development of the Arthurian legend.