Parchment is the lightly processed skin of calves, sheep, and goats, which gradually replaced papyrus, the millennia-old writing material that dates back to the 2nd century BC. According to legend, parchment was invented in Pergamon when it suffered from a ban on in the import of Egyptian papyrus. It is more likely that the process for parchment production (without tanning, only with a lime solution) was improved there. The advantages over papyrus are its smoother surface, greater sturdiness, and better durability; parchment can be written on both sides and can even be recycled (cf. Palimpsest). It was also better suited for the dissemination of the codex than papyrus.