If you were to write a recipe for a dish with very rich and complex flavours, you would probably include plenty of different ingredients, and a lot of time for preparation and cooking. This is a useful way to think about English and the reasons why it is so varied. A range of different languages contributed to its development, and it has had 1,500 years to marinate! Linguists refer to this as ‘time depth’.
The early history of English, like the history of England, is a story of multiple invasions. English first arrived with Anglo Saxon invaders from western Europe in the 5th and 6th centuries. Later came the Vikings, bringing with them Scandinavian languages and dialects of their own that had a significant impact on Old English. From 1066, French rule in England meant a new language was in circulation too and adding to Middle English as it developed. Latin has also contributed to the English language at various points throughout history. Latin and Latin-like words came into English via many different routes, particularly Christianity in the Middle Ages, a fashion for Latin during the Renaissance, and the need for new terms to describe scientific concepts as industry developed.
Dialects develop and change as people move and communicate. Some factors keep groups of people apart and prevent them from communicating. These can be geographical, such as mountains and rivers, or social, such as class, race, or gender prejudices. Other factors bring people together. These include geographical remoteness, close-knit communities, common interests and activities, and business and trade. The result is a vast range of regionally and socially distinctive ways of speaking or ‘dialects’.