The curriculum of every linguistic institute in our country includes the history of the language studied. This is justified both theoretically and practically.
As a social phenomenon, language is inseparable from society, since the people constituting the given society speak the given language. Every major event in the history of a certain people is reflected in its language. Some of these events affect the development of the language to such an extent that they may serve as some kind of landmarks in its history. Without the knowledge of such historical events it would be impossible to understand many facts in the language.
English is a West Germanic language that originated from Anglo-Frisian dialects brought to Britain in the mid 5th to 7th centuries AD by Anglo-Saxon settlers from what is now northwest Germany, west Denmark and the Netherlands, displacing the Celtic languages that previously predominated.