they've had plenty of time to solidify all of the languages into one. Though I'm not sure that there ever were more than one. The language they speak may have been given to them by the gods. Either way, there's just one main language spoken. There are probably some specialty languages. Secret tongues. But everyone would still speak the one main language of Ashara.
Since the world is full of all types of intelligent creatures that need to speak this language, and many, if not most, of those creatures do not possess lips, I needed to create a language that didn't require lips to speak it. So any names or other words I'm creating will not be using the letters B, F, M, P, V, or W.
Strangely, I have found as I create words for this language that they sound strikingly similar to many Native American words. Though the Native American languages are not devoid of these lip-produced sounds, they seem to be sparsely used. So when spoken aloud they remind me strongly of them.
As for other creatures that don't have the rest of the vocal apparatus such as a tongue or even lungs, they will just have to substitute similar sounds that they can make to the parts of words they want to pronounce. In much the same way that Scooby-Doo pronounces English. It's crude but it gets the job done.
I don't plan on creating the entire language like J.R.R. Tolkien did for the Middle Earth languages. But I do need to make words for all of the character names, cities, regions, animals, units of measure, and swear words.
Creating the character and place names is an obvious necessity. doing it for the units of measure is an existing convention of science fiction and fantasy that I'm choosing to go along with, and it makes sense. Using made-up swear words? Well that's just fun. Frak, Shazbot, Frel... Here's a list I found of hundreds of fictional swear words from various novels and TV shows:
Wow, I didn't realize there were so many. I've already come up with some. I'm going to need to think up a few more though. It'll be fun.