Language diffusion has played a significant role in with the two theories, Agricultural and Conquest. The diffusion of English was largely the result of population movements and conquests that took place between the 16th and 19th centuries and it has, in its traditional form. There are few obvious transfers of English-speaking people to new locations. Instead language diffusion has begun to work the other way; non-English languages are now being transferred into traditionally English-speaking areas (Spanish into the US, Bengali, Urdu, Punjabi into the UK). One consequence for the future of a diffused, multicentred, multi-standard English is that English may become more like a family of languages (ex. the Romance languages, all derived from Latin) rather than a single language. Already English-derived speech displays marked difference. On the other hand, the new electronic media, now current through the world, may work to preserve a relatively unitary language. Language diffusion ties in with a key role to the Theories of languages on how they diffused to certain parts.
The Agricultural Theory and the Conquest theory are the two most important theories of language today. The Agricultural Theory is the spread of culture that diffused the Proto-Indo-European language through Europe. This meant that the source area of the ancient language would have had to lie in an area of agricultural innovation. The language had hardly any words for other geographical landscapes but an abundant source of terms about their landscapes. The languages also had names for animals such as lions,