I have not done much in this respect but here you go:
Sunzaku lies about where Japan is on Earth. Below it lie the two civilizations that dominate the continent of Eastern Dorissadma; Hecizuotys, home to the Heocg and a coastal country and Azehar, an island country of well over 3000 islands (9 of which make up 98% of the land-area), home to the Azen. In terms of influence, Hecizuotys lies below Azehar, which basically dominated the entire continent in terms of influence (think Ancient China, kind of).
The three countries are the ones who made the three most important scripts of Dorissadma, Azenti's Surdhjan, Heocg's Sterbų, and Sunbyaku's Sungirnahashi. The first was Sterbų. Throughout all of Dorissadma, linguistic principles have been a matter of interest--the beginnings of Linguistics on Thōselqat as a whole started there. By the time Sterbų was made, the Heocg and Azen already had a theory of phonetics going, distinguishing consonants by their POA and MOA and vowels by their height and roundedness (Azenti has phonemic front rounded vowels and back unrounded vowels). Sterbų was an alphabet and collated its letters by POA and MOA, being arranged in the order <p b bh f t d dh ð....> and so on. It was developed by one woman, an epic poet named Wedhwas, for writing down her poems. It spread beyond her very quickly.
Sterbų, through Heocg traders (Hecizuotys was a trading nation), quickly spread to Azehar, where the Azen took it and modified it a little to fit their language's phonology (such as using the glyph for /ð/ for /ç/, and making new letters for sounds that weren't in Heocg like /ø/). The look also changed dramatically; Sterbų was built for being written with leaden pencils on tough wood imported from more forested regions, but the Azen wrote with delicate styli and ink on filmy paper stretched taut over wood, and thus didn't want to pierce the film. As of then, the Sun still had no writing system. They had a rudimentary idiographical system used for some minor records and stuff, but nothing considered true writing. A little more remote from Heocg (travelling from there to Sunzaku meant going through thick jungle and lands the Heocg didn't control), Sunzaku remained isolated from the advances in linguistics going on underneath.
However, a war ended up opening the country to the Heocg, who quickly came and seized the opportunity to peddle
usless junk things to the Sun. The Sun took to this quite well, and noticed that the people trading with them had this wood with funny scribbles on them. When a Sun lord named Ondagatsu inquired about this, the Heocg trader dealing with him (a woman named Snowṛðayas) said "It's writing. We record words down for later with it". Ondagatsu instantly demanded that Snowṛðayas teach him this writing.
The Sun quickly took up Sterbų but something felt off. They were prospering like never before, taking in the linguistic progress of Azehar and Hecizuotys, and trading very heavily, but their writing felt off. First of all, the lines of Sterbų were very poorly fitted to the brushes and ink the Sun used, resulting in writing looking like a huge amount of indiscriminate scribbles. This was fixed by simply modifying the shapes to fit brushes. But it wasn't from them. It was foreign.
However, one monk (named Shiovatta), was annoyed at this development. He reasoned that if the Sun were going to simply alter the shapes into their own kind, which looked almost nothing like the original glpyhs, why not just make a homegrown script? And what's the point of an alphabet built to write words like
Wṛðtom and
Strųgdhwal for a language like Sunbyaku, which simply possessed a simple (C)(y,v)V(n,r,l,m) syllable structure? He theorized the idea for a syllabary but had no way to actually develop it being too focused on monk duties.
Well, the lord of his lands, Rakunachi, found some of the old proto-writing in his lands and brought it to Shiovatta, interested in what he could do with it. Rakunachi then requested that the monk make a script based off of that, that would be easy to learn and effective for writing the language. Shiovatta did and ended up, using the ideographs and traditional Sun abstract art as inspiration, creating the syllabary. Use of it quickly spread.
Shiovatta after creating it spent most of his time writing Linguistic papers, his most treasured one being an functional grammar for Azenti.
And there, that's the story.