Anglo-Norman language general use of the word "acre" for land measurement in Normandy until metrication in the 19th century, but these words are probably linguistic traces of Saxon or Anglo-Scandinavian settlements between the 4th and the 10th centuries in Normandy. Otherwise the direct influence of English in mainland Norman (such as "smogler" - to smuggle) is from direct contact in later centuries with English, rather than Anglo-Norman. When the Normans invaded England, Anglo-Saxon literature had reached a very high level of development. The important Benedictine monasteries both wrote chronicles and guarded other works in Old English. However, with the arrival of the
Anglo-Norman literature of Henry IV that English became the native tongue of the kings of England. The language had undergone certain changes which distinguished it from the Old Norman spoken in Normandy, as can be seen from graphical characteristics, from which certain rules of pronunciation are to be inferred. An Anglo-Norman variety of French continued to exist into the early 15th century, though it was in decline at least from the 1360s, when it was deemed insufficiently well known to be used for pleading in court. Great prestige continued to be enjoyed by the French language, however; in the late 14th century,