The chronology of the sceattas is also very hard to unravel. Some of the earliest series use the same designs as the pale gold thrymsas (similar to the continental ; notionally one-third of a pure gold solidus) and, by analogy with coins from the better-understood Frankish material, can be dated to the 680s. It is known that sceattas were minted in the Frisian town of Dorestad (just south of Utrecht in the Netherlands); they were a commonly circulating currency in the Frankish realm until the monetary reform of Pepin the Short instituted at Ver in 755.