5,000 troops garrisoned there and in its early stages York operated a command economy. Production included military pottery until the mid-third 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. New trading opportunities led local people to create a permanent civilian settlement on the south-west bank of the River Ouse opposite the fortress. By 237 it had been made a colonia one of only four in Britain and the others were founded for retired soldiers. York was self-governing, with a council made up of rich locals, including merchants, and veteran soldiers. Evidence of Roman religious beliefs in York have been found including altars to Mars, Hercules, Jupiter and Fortune, while phallic amulets are the most commonly found type of good luck charm. In terms of number of reference the most popular deities were the spiritual representation (genius) of York and the Mother Goddess; there is also evidence of local or regional deities. There was also a Christian community in York although it is not known when it was first formed and there is virtually no archaeological record of it. The first evidence of this community is a document noting the attendance of Bishop Eborius of Eboracum at the Council of Arles (314), and bishops also attended the First Council of Nicaea in 325, the Council of Serdica, and the Council of Ariminum. By 400 AD York's fortunes had changed for the worse. The town was undergoing periodic winter floods from the rivers Ouse and Foss, its wharf-side facilities were buried under several feet of silt and the primary Roman bridge connecting the town with the fortress may have become derelict. By this time Eboracum was probably no longer a population centre, though it likely remained a centre of authority. While the colonia remained above flood levels, it was largely abandoned as well, retaining only a small ribbon of population for a time. Early Middle Ages Post-Roman Ebrauc There is little written evidence about York in the centuries following the Roman withdrawal from Britain in 410, a pattern repeated throughout Sub-Roman Britain. There is archaeological evidence for continued settlement at York near the Ouse in the 5th century, and private Roman houses, especially suburban villas, remained occupied after the Roman withdrawal. Some scholars have suggested that York remained a significant regional centre for the Britons, based