Geography determines how languages form, more specifically in the ways that they separate language-speakers. This field is important to conlangers, since the natural features can divide a group of people for generations until they cannot understand each other.
The natural features would have to be presented between these groups in order to language shift to occur. These include mountain ranges, valleys, islands, and rivers. Unless the groups of language-speakers can communicate by some means, whether by a boat or a road, there will be isolation that can occur. That is why more wooded areas of a country usually contain dialects or languages that have barely changed in many years, retaining a conservative vocabulary, phonology, and grammar.
Guy Deutscher, in The Unfolding of Language, mentioned how indigenous and ancient societies tend to have complicated grammars whereas the more modern languages, such as English, tend to have lax grammars. He speculates that this is because smaller, tightly knitted societies in the past tended to interact more with their intimates than with strangers, whereas empires and city-states that tend to house diverse populations would need to develop simpler lexicons and grammar.
Of course, it has also been speculated that English is itself a creole language, which married the Old English spoken by the Saxon settlers of Britain with the French spoken by the Norman invaders who arrived in 1066 AD. Languages do not just \”simplify\” simply because they are introduced to a wide variety of languages and need to creolize in order for all diverse language speakers to understand each other, rather they do so because they are generally in positions where they must adapt.
Isolated language-speakers, on the other hand, neither consist of sprawling urban centers nor conquered territory, so they are in no position to adapt their own languages. Nonetheless, it should always be an option to include complex grammar into a conlang locally based in an isolated area, such as a valley or an island. Although these languages would be from the same language family tree, they would be completely different in their grammatical conventions.
This was definitely the case with Icelandic, which bears a much more close resemblance to the Old Norse spoken by the original Viking settlers than Modern Norse spoken in Norway proper. This is, of course, because there is a wide sea that separates Scandinavia from themselves.
So consider this, if there is a chance that language family trees would form in a mythocosmography, then it would be important to note that geography must play a role in determining the divergence of languages. Rivers, mountains, and islands should not just be blots to fill in space on a fantasy map, rather they need to determine whether a language retains its elements or if they change. If the migration involves meeting and intermingling with another group of people, then the language would change; if not, then the language remains the same.
Sources
- Brandy Ryan, \”Middle English as Creole: “Still trying not to refer to you lot as ‘bloody colonials’”\”, University of Toronto, 2005
- Curzan, Anne and Michael Adams. How English Works: A Linguistic Introduction. 3rd Edition. Pearson. 2012.
- Deutscher, Guy. The Unfolding of Language: An Evolutionary Tour of Mankind’s Greatest Invention. 1st Edition. Metropolitan Books. 2006.