Superficially, Charlemagne seemed to have imposed himself on Benevento. Arechis had paid tribute and one of his sons was being held hostage as a guarantee of Benevento's loyalty. Frankish influence was also given formal expression. Traditionally Benevento had produced and used gold coinage, but from 787 the Beneventan mint began to strike silver coins too. The new coins were similar to those issued by Charlemagne's Frankish kingdom. Both the new silver and the traditional gold coins, as well as Beneventan legal documents, all started to include Charlemagne's name and title alongside those of Arechis. The inclusion of titles on coins and in charters was considered an important marker of political authority.