Papyrus was considered the only proper writing material in late antiquity in the Mediterranean basin. It was made from papyrus reeds, especially as grown along the Nile. The reeds would be slit (they're sticky on the inside), spread out, and pressed together into several different layers. When dried, they made a good writing surface. Although parchment (made from animal skin) was known, it was considered inferior. Saint Augustine apologized in one letter for writing on parchment, because he'd run out of papyrus. I'm not trying to insult you or anything! (not his exact words, but his meaning).
The difficulty with papyrus is that it has to be kept dry. If it gets damp, it can disintegrate back into pieces of reed. This is a problem once you get into Europe's damper climate. The other problem is access to the papyrus reeds themselves, as of course they won't grow in most of Europe.
The popes of late antiquity/the early Middle Ages wrote on papyrus (see more here on early medieval popes). They really only became the heads of western Christendom in the sixth century, at least in their own minds (almost no one in Europe would have been able to tell you who was pope at any given time), and they got in a couple of crates of papyrus, to have plenty of writing material on hand. With the rise of Islam in the seventh century, their access to Egypt and papyrus reeds was cut off, so it was a good thing they had stockpiled.
Over the next four centuries, through all sorts of upheavals, the Lateran palace in Rome maintained their papyrus stockpile. There must have been a special room where it could be kept warm and dry, although we have no details. Slowly they worked through it, writing letters to kings, to bishops, to monasteries.
The problem was that the people they wrote to didn't have nearly as good conditions for storing papyrus. Charlemagne's grandfather, in the early eighth century, had a special volume drawn up, copying every missive the family had had from the pope copied onto parchment. Most of the documents were less than fifty years old, but they were already disintegrating. Bishops and monasteries too felt the need to copy their precious papal documents onto something more permanent than papyrus.
Very few early medieval papyrus documents survive. We do know that through the seventh century most towns in the old Roman empire had municipal archives, where important documents were stored, but these all disappeared, and probably the fragility of papyrus had a lot to do with it. A few monasteries managed to keep a handful of papyrus documents, such as Saint-Denis, which scraped off the ink, turned the papyrus over, and forged new and better papal confirmations on the back. By the eighth century most of Europe switched to parchment.
But not the popes! They hoarded their papyrus until it finally gave out in the eleventh century. During this time they also continued to write their documents in what is known as late Roman cursive, big flowing and looping letters that must have been increasingly hard to read by anyone north of Italy. The rest of Europe switched after the eighth century to what is known as Caroline miniscule, which looks a whole lot like modern printing, for the excellent reason that modern printing is derived from it. What's this? many a bishop must have thought, getting a piece of papyrus with almost indecipherable writing on it from the pope.
German popes in the mid-eleventh century brought the papacy into European relevance with parchment and Caroline miniscule as well as assertions of being the top of the church hierarchy, but that's another story. (And of course "papal infallibility" was first proclaimed in the nineteenth century.)
Our modern word paper is derived from the word papyrus. First Arabs in the thirteenth century and then most of Europe in the fourteenth century figured out that paper, made from cotton, worked a whole lot better than papyrus reeds.
© C. Dale Brittain 2024
For more on the medieval church and medieval literacy, see my ebook, Positively Medieval: Life and Society in the Middle Ages. Also available in paperback.