| It wasn't. Clay tablets were not expensive- all you had to do was walk down to the riverbank and grab some clay. What may have been expensive was the services of scribes to write and read those clay tablets- and as they were heavier than papyrus or vellum, moving and storing them was also expensive. So there was no mass-market literature- that had to wait for printing. What survives are sacred texts, administrative records, and letters related to government or business (like the infamous complaint letter to Ea-Nasir). But because clay is much cheaper than parchment or even papyrus, what also survives- which doesn't survive in anything like as similar numbers from cultures that wrote on parchment/papyrus AFAIK- is scribal students' exercises, because clay was so easy to get that they would just throw away their completed exercises and pick up a new tablet rather than recycle them. (One important exception here is birchbark- at Novgorod, in the middle of a vast birch forest, birchbark was almost as cheap as clay in Mesopotamia. So medieval children's doodles [0] on it have survived. Another is papyrus written by the Jewish community of Cairo, who had a religiously-motivated aversion to throwing away or erasing anything written. [1]) This means that we have a lot of copies of the beginning of texts written on clay, as students would copy them out for practice. In contrast, if a text was written on parchment, the middle is more likely to survive as it was less exposed to pests and the elements. [0] https://lithub.com/onfim-wuz-here-on-the-unlikely-art-of-a-m... [1]https://en.wikipedia.org/wiki/Cairo_Geniza |