Eboracum workshops growing up outside the fortress to supply the needs of the 5,000 troops garrisoned there. Production included military pottery until the mid-3rd century, military tile kilns have been found in the Aldwark-Peasholme Green area, glassworking at Coppergate, metalworks and leatherworks producing military equipment in Tanner Row. In the Roman period, Eboracum was the major manufacturing centre for Whitby Jet. Known as "gagates" in Latin, it was used from the early 3rd century as material for jewelry and was exported from here throughout Britain and into Europe. Examples found in York take the form of rings, bracelets, necklaces, and pendants
Deira would mean "the people of the Derwent", a derivation also found in the Latin name for Malton, "Derventio". The modern Gaelic 'Doire' (pronounced Dirruh/Durruh) is the same word. The origin of the name for County Londonderry and city of Derry stems from this word with an oak being featured on the crest of Derry GAA. According to Simeon of Durham (writing early in the 12th century), it extended from the Humber to the Tyne, but the land was waste north of the Tees. After the Brythonic kingdom centred on "Eboracum", which may have been called Ebrauc, was taken by King