surviving gold coins from Offa's reign. One is a copy of an Abbasid dinar struck in 774 by Caliph Al-Mansur, with "Offa Rex" centred on the reverse. It is clear that the moneyer had no understanding of Arabic as the Arabic text contains many errors. The coin may have been produced to trade with Islamic Spain; or it may be part of the annual payment of 365 mancuses that Offa promised to Rome. There are other Western copies of Abbasid dinars of the period, but it is not known whether they are English or Frankish. Two other English gold coins of the period survive, from two moneyers, Pendraed and Ciolheard: the former is thought to be from Offa's reign but the latter may belong either to Offa's reign or to that of Coenwulf, who came to the throne in 796. Nothing definite is known about their use, but they may have been struck to be used as alms.Stenton, Anglo-Saxon England, pp. 223–224. Although many of the coins bear the name of a moneyer, there is no indication of the mint where each coin was struck. As a result, the number and location of mints used by Offa is uncertain. Current opinion is that there were four mints, in Canterbury, Rochester, East Anglia and London. Stature The title Offa used on most of his charters was "rex Merciorium", or "king of the Mercians", though this was occasionally extended to "king of the Mercians and surrounding nations". Some of his charters use the title "Rex Anglorum," or "King of the English," and this has been seen as a sweeping statement of his power. There is debate on this point, however, as several of the charters in which Offa is named "Rex Anglorum" are of doubtful authenticity. They may represent later forgeries of the 10th century, when this title was standard for kings of England. The best evidence for Offa's use of this title comes from coins, not charters: there are some pennies with inscribed, but it is not regarded as definite that this stood for "Offa Rex Anglorum." In Anglo-Saxon England, Stenton argued that Offa was perhaps the greatest king of the English kingdoms, commenting that "no other Anglo-Saxon king ever regarded the world at large with so ... acute a political sense". Many historians regard Offa's achievements as second only to Alfred the Great among the Anglo-Saxon kings. Offa's reign has