There was a Byzantine Dark Age in the 7th and 8th Centuries where perfume lived under the rubble of previous cities hiding from Arabic and other invaders. The Roman aqueducts went into disrepair and people went back to drinking from wells. There was a major population collapse. They did make some cool devices though like clocks and mechanical lions, as well as Greek fire. http://www.patheos.com/blogs/anxiousbench/2016/06/the-byzant...