The origins of the English language can be traced back to the Saxon and other Germanic settlers in Britain beginning in the 5th century CE. The English language's unusual nature can be attributed to the diverse linguistic origins of the groups that contributed to its development and their role in English society. Although English belongs to the Germanic language family and its grammatical and syntactical rules reflect this, English vocabulary can be seen to be from multiple origins. In fact, a large part of the vocabulary was not derived from the Germanic languages at all but is rather of Latin origin. This can be explained by the influence on Old English of Old French and Latin during the Norman Invasion in the 11th century. By the time of the Norman Invasion, Old English was already a language, with both its grammar and vocabulary based in the Germanic language family. However, the establishment of a ruling class who spoke a Romance language caused significant changes in the indigenous tongue. It is also interesting to note that there is a distinct correlation between the length of a word and its origin – most of the shorter words in the English language are derived from the Germanic languages, whereas the longer words are from a Latin background. One theory to explain this is that these more elaborate and complex words were primarily used by the elite after the Norman Invasion – who would have favored a Latin-based (or Romance) vocabulary – whereas words with the same meaning in the Old English were used primarily by the lower classes and thus fell into disuse. Modern English words, then, concerning more complex and theoretical rather than utilitarian ideas (astronomy, poetry, and epistemology), can generally be found to be of Romance origin, whereas more mundane words, such as pronouns and auxiliary verbs, can be traced back to a Germanic origin.