Since the beginning of the 5th century, Saxons from the region between the lower Elbe and the Weser made their way to the
British coast together with Angles from Schleswig and settled in the south and east of the British island. The English father of the church, Beda Venerabilis, speaks in his book ‘Historia ecclesiastical gentis Anglorum’ in chapter 1, page 15 of the legendary Saxon leaders Hengest and Horsa who were invited by the British king to come and brought Angles and Jutes (a tribe whose home is assumed to have been in Denmark) with them. The English place-names Wessex, Sussex and Essex are remnants of this time. According to Mitchell 1995, 13 it is not clear whether "the migrants came in large numbers and drove out the Celtic-speaking inhabitants into Wales, where many of their descendants still speak Welsh, and Cornwall, where Cornish was spoken until
c. 1800" or if it is not as well possible that "there was no mass migration but only a seizure of power by a new ruling elite who imposed their Germanic culture and
language on the Celts".
However, the Anglo-Saxons brought a Germanic language to England and this language with its differences caused the development of the four main
dialects of Old English, which are Northumbrian, Mercian, Kentish, and West Saxon. Under King Alfred who ruled from 871 to 899 the West- Saxon, dialect became the standard language of England.
On the continent language developed in a different way. What is now the Saxon tribe did not only inhabit Germany but also by Franks who lived all over France and in, the western part of Germany and led several wars against the Saxons. At the North Sea coast of Germany and the Netherlands settled Alamanni, Bavarians, and Thuringians inhabited Frisians and the southern part of Germany. These groups were important in the formation of German dialects.
Before going more into detail it is important to know that Germany was divided into two parts, the northern one where people spoke Low German dialects which were descendants of Old Saxon and Old Low Franconian and the southern one where Old High German was spoken. It consisted of different Frankish dialects. The boundary between these areas lay between Dortmund and Cologne in the west, Magdeburg, and Erfurt in the east. This line was an isogloss, which means that it separated areas where the same word was pronounced differently. Therefore it is also called the ‘maken/machen’ line because the German word for "make" is pronounced with
in the dialects spoken to the north of the line, and with (as in German "ach") to the south of it.