Anglo-Norman, also known as Anglo-Norman French, is a variety of the langues d'oïl that was used in England and, to a lesser extent, elsewhere in the British Isles during the Anglo-Norman period. When William the Conqueror led the Norman invasion of England in 1066, he, his nobles, and many of his followers from Normandy, but also those from northern and western France, spoke a range of Oïl dialects (Northern French dialects). One of these was Norman. Other followers spoke varieties of the Picard language or western French. This amalgam developed into the unique insular dialect now known as Anglo-Norman French, which was commonly used for literary and eventually administrative purposes from the 12th until the 15th century. It is difficult to know much about what was actually spoken, as wha