奇怪的关于as的用法

《白勇语法》第七章之比较结构32题中：

Salt deposits and moisture threaten to destroy the Mohenjo-Daro excavation in Pakistan, the site of an ancient cilivilization that fourished at the same time as the civilizations in the Nile dalta and the river valleys of the Tigris and Euphrates.

答案就是划线句子，as在这里到底是什么用法呢？如果作连词表比较后面应该连接句子？谁能指点一下，谢谢！

翻了下上XDF时的笔记  

AS 作介词+N   eg. as a student

XDF蓝本P258 第69题里就这么用

GWD-8-Q1也是

呵呵，我觉得这里的as是表“像”的意思，不是表“作为”，而蓝本P258.69是当“作为”讲的，当“作为”作介词加名词

Open to discuss...

the same time as

 个人觉得，后面省略了did（如下）。期中的AS表示“就如。。。一样”

Salt deposits and moisture threaten to destroy the Mohenjo-Daro excavation in Pakistan, the site of an ancient cilivilization that fourished at the same time as the civilizations (did)in the Nile dalta and the river valleys of the Tigris and Euphrates.