The Arab dinar was in common use throughout North Italy in the 7th and 8th centuries as a functional gold coinage and likely returned to England via pilgrims to Rome who acquired them either as souvenirs or in trade. In Mercia, they served as the inspiration for the mancus, a semi-functional gold coinage whose name is most probably an Old English bastardisation of the Arabic 'manqūsh' - slang for struck coinage such as the dinar. Using the dinar as a base comparison, the mancus was established as both a weight of gold equal in value to 30d of silver, and a coin comprising that same amount of gold.

The two terms are often used interchangeably which can make life interesting, but it's interesting that the Mercian - and later English - mancus never appears to have been a coin designed for widespread economic use, a niche filled very thoroughly by the Old English silver penny. It is worth noting that, apart from the 'Mercian dinar', mancuses bear typically English obverse and reverse designs, such as those on this mancus of Coenwulf. This is just to illustrate that the use of an original dinar base design by Offa's moneyer in this case was a clear design choice rather than just the rote recreation of an actual dinar just with Offa's name overstamped.

Mancus issues (of which we have very few extant examples) appear to have been almost entirely ceremonial in purpose; prestige gifts for a king to bestow to his gesith, to a witan or to foreign dignitaries in a display of generosity and benevolence. It's in this context that we can likely place the Mercian dinar: English kings were common donors of tribute to the Papacy. The Anglo-Saxon Chronicle keeps particularly detailed records of King Alfred of Wessex's donations to the Lateran, but the custom was commonplace throughout the period. For the most part, these tributes were rendered in pennies, and indeed Papal treasuries have provided some excellent numismatic specimens of a wide array of English penny issues. One hoard found in 1927 purportedly during the construction of a wireless station at the Vatican (and tragically sold off in London almost immediately, although painstakingly researched for the BNJ by M.A. O'Donovan) contained 18 pennies of Alfred of Wessex, 437 of Edward the Elder, and 35 of Æthelstan. The Mercian dinar is another Roman find, and jt's very likely that it was minted by Offa as part of a Mercian tribute to the Papacy. The decision to render tribute in replica dinars rather than in English pennies may have been simply an issue of prestige, but the conscious attempt to replicate the dinar design rather than simply using an English mancus design on a coin of the equivalent weight suggests that Offa may have intended the coinage to have been immediately functional and able to be used directly by the Pope rather than as a value weight that would require exchange or re-stamping.