To me this anecdote does not pass the smell test, at least as you have presented it. The reason is that the mass production of wood-pulp paper is a fairly recent historical phenomenon, dating from the 1840s. Before then, of course, paper was made from various other plants, including papyrus reeds, cotton, rice, and flax, but never in such quantities to produce a large wall. It could be that you are misremembering your story, that there was a translation error, or that the story is just wrong, but it doesn't square with the history of paper and cardboard production. Cardboard in its modern form simply would not have existed before the 1840s.