Set during the reign of Richard II reigned 1377 to 1399.
Reference to Pre-Inca: Upanqui -ruled in the 1400s
Reference to Black Letter or Old English Script (But this is not necessarily the same as Old English, which ends at about 1100)

Excerpt of Black Letter from the Bible: from The Encyclopedia Britannica
 

Black Death in London: 1348: from The Encyclopedia Britannica
 
 

Image of Black Death: from the Encyclopedia Britannica.