I found this Wikipedia article about central Asian music. The bowed string seems to have originated in central Asia with instruments sometimes using silk strings.
There is a link to an important mongolian instrument. In China, I saw a variation on the idea, and inspected it to discover if it had a soundpost, which it did.
The articles fall down in not mentioning a soundpost. I believe it is likely to be there, and that would reinforce the idea that coupling the top and back is an important concept in a large class of instruments.