请问as引导什么从句？具体分析一下

indeed,the Egyptians began sending letters from about 2000 BC ,as did the Chinese a thousand years later.

as 引起一个状语从句，从句中为了强调而倒装。as did the Chinese a thousand years later，助动词（did ）＋主语（the Chinese) ＋省去的主要动词（began sending letters)

就是等同于which 之类的呀,和他们是一样的功能,先行词只不过有一层正如---的意思

严格说来也是