Birrus/Byrrus

[Carlton Bach]

I realise that SCA-sites do not count as primary sources, but I found a reference to a provincial Roman garment called the birrus or byrrus here

http://www.housebarra.com/EP/ep02/19byrrus.html

and I am wondering what to make of their interpretation. Unfortunately, the literature quoted in support is not currently available to me. Has anyone come across depictions like these? Is a 'sleeved cape' at all credible for the provinces?` It sounds awfully medieval to me, but if there is evidence for it, I'd like to make one.