The tenth century saw the gradual unification of England, as the kings of Wessex (an Anglo-Saxon kingdom, south of the River Thames) expanded their authority to the north and east. England was permanently unified from the reign of Edgar (959-75). The earlier, gradual unification was not reflected in the coinage, and a variety of different regional styles of coinage existed, reflecting the regional identities of the various former kingdoms. This continued to be the case until shortly before the end of Edgar's reign. Edgar introduced a new type of coin across the whole of England: the first English national coinage. One side showed a royal portrait derived from late Roman coins, with the king's name and title. The other had a small cross in the centre, with the name of the moneyer and mint responsible for issuing the coin around the outside. There were a large number of mints issuing coins in this period, and the new system meant that any coin could be used throughout the country, but that it was still possible to trace each coin back to its original mint and moneyer if there was any doubt about quality. This coin was struck by the moneyer Osulf. Although the details of the design changed every few years, this broad pattern of coinage lasted for over two centuries.