As (Roman coin) as, the (2), (2), . After the as had been issued as a cast coin for about seventy years, and its weight had been reduced in several stages, a as was introduced (meaning that it weighed one-sixth of a pound). At about the same time a silver coin, the denarius, was also introduced. Earlier Roman silver coins had been struck on the Greek weight standards that facilitated their use in southern Italy and across the Adriatic, but all Roman coins were now on a Roman weight standard. The denarius, or 'tenner', was at first tariffed at ten asses, but in
Sino-Roman relations starting in the 6th century AD, Chinese varieties were still considered to be of higher quality. This theory is supported by the discovery of a Byzantine "solidus" minted during the reign of Justin II found in a Sui-dynasty tomb of Shanxi province in 1953, among other Byzantine coins found at various sites. Chinese histories offer descriptions of Roman and Byzantine coins. The "Weilüe", "Book of the Later Han", "Book of Jin", as well as the later "Wenxian Tongkao" noted how ten ancient Roman silver coins were worth one Roman gold coin. The Roman golden "aureus" was worth about twenty-five silver