Did Mandarin Pinyin `chiang` used to exist? Came across this today:


  《廣韻·平·江》：“，短敞衣也，丑江切。”


 has MSM pronunciation chuāng but if we take 丑江切 that means we have ch + iang = chiang.

Other characters with 丑江切 seem to include:

䚎 (MSM: also chuāng)

憃 (MSM: chōng)

广韵 isn't exactly modern and 丑江切 seems to come out differently in different cases today.

What I'm mainly curious about here though is:

Did (modern) Mandarin Pinyin chiang used to exist?
The 反切 in 廣韻 use Middle Chinese pronunciation, so one cannot take the modern readings of the 反切 上下字 as a guide to how a word might be pronounced.

In this case, you are looking at words in the 江 rhyme category. These words have developed a -j- medial in Mandarin (when there is a velar initial) that was not present in Middle Chinese. Other dialects have not. Compare, for instance, the Cantonese pronunciation of 江 "gong".

Although  is not a "living" character, words which are in the same initial and rhyme categories are still around, such as 撞 zhuang. This is the regular development. 

Mandarin has never had retroflex initials followed by medial -j-; in fact, this would seem to be a very unlikely combination in any language.