English Literature is focused on English-language literature rather than the literature of England, so that it includes writers from Scotland, Wales, the Crown dependencies, and the whole of Ireland, as well as literature in English from countries of the former British Empire, including the United States. However, until the early 19th century, it only deals with the literature of the United Kingdom, the Crown dependencies and Ireland. It does not include literature written in the other languages of Britain.
The English language has developed over the course of more than 1,400 years. The earliest forms of English, a set of Anglo-Frisian dialects brought to Great Britain by Anglo-Saxon settlers in the fifth century, are called Old English. Middle English began in the late 11th century with the Norman conquest of England. Early Modern English began in the late 15th century with the introduction of the printing press to London and the King James Bible as well as the Great Vowel Shift. Through the influence of the British Empire, the English language has spread around the world since the 17th century. (from https://en.wikipedia.org/wiki/English_literature)