The mint's extraordinary productivity in the earlier 10th century is rather puzzling. Proximity to the mines of North Wales (Northgalis), believed to have yielded silver along with the lead which was their chief product, has been adduced as a reason for its unusually high output, but there is no evidence that Wales ever produced silver in the quantity necessary for the vast numbers of coins minted in Chester.
North Wales comprises the island of Anglesey, the Lleyn Peninsula and the Snowdonia mountain range, together with the catchments of the Rivers Conwy, Clwyd and Dee. Traditionally, most of North Wales was covered by the kingdom of Gwynedd. More plausibly, it has been suggested that the city was the centre for the collection of bullion and tribute acquired by Æthelflæd and Æthelstan as a result of their military victories over the Danes and the Welsh princes. For many purposes Wales can be divided into only three regions, North Wales, South Wales and West Wales. In this scenario the boundary between North Wales and West Wales is marked by the Cerdigion Powys Border. Although there is nothing to suggest that Æthelstan ever exacted tribute on the scale or with the regularity necessary to sustain the output of the mint in his reign, large amounts of bullion were probably obtained from the Vikings of the western Danelaw, either as plunder from those who had resisted and fled, or as offerings from those who wished to reach an accommodation with the new regime.
The extensive coinage may also have been stimulated by a favourable balance of trade. Chester was a centre for the export of valuable commodities needed in Ireland, the bullion received in return being made into coin on the spot for circulation in England. That trade would naturally have been focused on Dublin, which by the mid 10th century had become the principal port of the Irish Sea and one of the richest of all Viking towns. The extent of the traffic between the two centres is apparent from the large amount of Chester ware exported to Dublin by the time of Æthelstan. Other exports possibly included salt, much needed in Dublin to preserve fish and treat hides, disc brooches and other items of Anglo-Saxon metalwork, cloth, and slaves. The importance and value of the last commodity has almost certainly been underestimated.
The Dublin Norsemen's continuing need for slaves, apparent from the long-lasting trade with Bristol, was probably serviced, as later, by those penally enslaved and by captives taken on the turbulent frontier between England and Wales, for whom Chester would have been the obvious market.
Trade between Chester and Dublin was not all one way. The large number of 10th-century coin hoards from Ireland and western Britain, in which Chesterminted coins were very prominent, points to a considerable outflow of silver from Chester. Although the hoards may have been looted from England, the fact that their age-structure was consistently different from that of contemporary English ones suggests that the coins had a local circulation in a country otherwise lacking them, and hence that they were used in trade. The avoidance of portraiture by the Chester mint before 970 may have been partly to accommodate the taste of the Norsemen of Dublin. Almost nothing is known of the goods imported into Chester from Dublin. Later evidence suggests that they were mainly furs, hides, fish, and agricultural produce. The only commodity known to have been imported before 1066 was marten furs, the subject of a royal right of pre-emption and therefore probably a high-value item. Almost certainly they came via Dublin, where they are known to have been a prized export.
The discovery at Coppergate in York of a lead customs tag produced at the Chester mint in Eadwig's reign, and apparently attached to merchandise under the supervision of royal officials, suggests a cross Pennine trade in Irish goods imported at Chester. The prominence of Chester coins in southern England in the earlier 10th century during periods of fairly slack minting in London implies a further trade route running between the South-East and the North-West, along which Chester coin passed to purchase commodities in the South for export to Ireland and the Western Isles. The rise and fall of such different trade routes may help to explain fluctuations in the production of coin at Chester in the 10th century. The decline of the Chester mint has long been attributed to a Viking raid on Cheshire in 980. Three of the four Anglo-Saxon coin hoards found in the city, those from Castle Esplanade, Pemberton's Parlour, and Eastgate Street, have been assigned to roughly the same period and interpreted as linked to that raid. A period of dereliction after the end of occupation in the harbour area in the south of the city has also been thought to reflect its effects, and it has been argued that the rise of Bristol and the beginning of Chester's eclipse as the principal port for the Dublin trade dated from that time.
In particular, it is clear that Chester did not play an important part in Edgar's reform of the coinage c. 973, well before the raid. The number of moneyers declined dramatically from c. 20 immediately before the reform to a mere five or so during the reform itself. Such small numbers continued throughout the reign of Edward the Martyr (975-8) and during the early issues of Æthelred II (978-1016), and were associated with a huge decline in output and the end of die-cutting at Chester. Die production for the Reform issue was centred upon London and Winchester, but most major mints quickly re-emerged as die-cutting centres, Chester alone among the great northern mints continuing to receive its dies from Winchester until the 990s.
Assessment of the decline is also affected by redatings of the Chester coin hoards. Those from Castle Esplanade and Eastgate Street were probably deposited c. 965 and c. 970 respectively, well before the renewal of Viking hostilities in the Irish Sea. Only the Pemberton's Parlour hoard is likely to have been buried in 980 at the time of the Viking raid. That raid has been overused as a reason for the decline of the Chester mint and cannot account for the catastrophic falling-off in 973, presumably part of some more general process since the other north-western mints, especially Derby, show a like pattern. One possible explanation lies in long-term economic developments. The shift away from the north-western mints towards those of eastern England in the late 10th century may have owed as much to changes in trading patterns in response to the opening up of the German silver mines in the 960s as to the disruption of traffic across the Irish Sea.