Scholars generally ascribe the loss of word endings in English not to the Norman Conquest, which happened afterward, but to the repeated invasions and coastal settlements of Norse raiders across eastern England during the 9th and 10th centuries. As Old Norse and Anglo-Saxon were cognate languages, dropping the endings and creating a grammar based on word order rather than stem+ending meant communication could more easily be accomplished between inhabitants and new (heavily armed) settlers. Over time, custom and interbreeding resulted in the development of non-inflected early English in the south and east; conversely aspects of inflected English persisted longer in the south and west - which is why Chaucer wrote the Canterbury Tales in non-inflected English while the contemporaneous Gawain poet wrote in an English that still had the marks of Anglo-Saxon alliteration and the remnants of inflection.