在罗马帝国时期（公元前37年-公元476年），制造紫色染料非常困难。

During the time of the roman Empire (37 BC-476 AD), it was very difficult to make purple dye.

youdao

这种做法可以追溯到罗马帝国时期。

The practice dates back to at the least the Roman Empire.

youdao

但想象一下在罗马帝国时期。

But think of the Roman empire.

youdao

Another characteristic of these years, which scholars refer to as the Dark Ages, just as they do the years after the fall of the Roman Empire-- dark for two reasons. Dark, in the most obvious way, because we don't have any writing, no record of them.

这也是这段时期的另一个特征,学者们称之为,黑暗时代,他们也是这么称呼,罗马帝国陷落后的那段时期的,称黑暗主要有两个原因,黑暗,最明显的理由,是因为我们没有任何关于他们的史料和记录

耶鲁公开课 - 古希腊历史简介课程节选