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
Eboracum the area known as the Brigantes by the Romans became a Roman client state. When their leadership changed becoming more hostile to Rome, Roman General Quintus Petillius Cerialis led the Ninth Legion north from Lincoln across the Humber. Eboracum was founded in 71 AD when Cerialis and the Ninth Legion constructed a military fortress (castra) on flat ground above the River Ouse near its junction with the River Foss. In the same year Cerialis was appointed Governor of Britain. A legion at full strength at that time numbered some 5,500 men, and provided new trading opportunities for enterprising local people,