Chat in Offa

Offa of Mercia or Offa I of Mercia, of whom the exact date of birth is unknown, and died in 796, in the month of July he was king of the kingdom of Mercia between the year 757 and the date of his death. During his reign, with a duration of almost 40 years, it is noteworthy, on the one hand, the introduction into the monetary system of penny, which has remained in use until today, as well as the wall of Offa, a defensive wall before the Celtic tribes of present-day Wales and Cornwall, part of whose remains are still visible more than a thousand years later. On the other hand, it dominated most of England located south of the Humber River.

His long reign marked strongly the future of England, to the point that it was the first to be called King of the English or Rex Anglorum, ie, King of England, the first of the Anglo-Saxons to adopt this denomination. The importance of his figure at the time in which he lived is shown by the fact that he maintained with Carlomagno, king of the Franks, negotiations about the possible marriage of their respective children, although finally these negotiations did not bear fruit. Thus, Offa possessed within the island of Great Britain an undisputed supremacy before the rest of the kings of the Anglo-Saxon Heptarchy. Finally, the figure of Offa and the network of relations interwoven with the main political powers of the Europe of his time mark the end of what contemporary historiography knows as the "dark centuries" of the History of England.

https://en.wikipedia.org/wiki/Offa_of_Mercia