Complex sentence: Its use was forbidden in 1220 by king Frederick II for being less durable then parchment paper, however it has continued to be produced and used, so that, in the eighteenth century another twenty mills were active in Amalfi and the nearby cities.
Split into simpler sentences: Its use was forbidden in 1220 by king Frederick II for being less durable then parchment paper. However, it continued to be produced, and in the eighteenth century another twenty mills were active in Amalfi and the nearby cities.