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
Proto-Germanic language of Proto-Indo-European and its gradual divergence into a separate language. As it is probable that the development of this sound shift spanned a considerable time (several centuries), Proto-Germanic cannot adequately be reconstructed as a simple node in a tree model but rather represents a phase of development that may span close to a thousand years. The end of the Common Germanic period is reached with the beginning of the Migration Period in the fourth century. The alternative term "Germanic parent language" may be used to include a larger scope of linguistic developments, spanning the Nordic Bronze Age and Pre-Roman Iron