Ironically, some parts of Iraq have enormous numbers of mud tablets, and Saddam made quite a bit of money selling thousands of them.
They were the mail of the day, and caravans made a lot of money by transporting hundreds of them from city to city, over many centuries. And like most mail, once read, they were discarded. Most of it was business mail, news and personal correspondence.
The funny part is in the content of some of these letters. One expert compiled a list of some cuneiform writings that would not be out of place today.
For example, one was from a student asking his parents for money, because his peers wore better clothes and ate better food than he could afford, and it was embarrassing.
Another was a creditor sent “third warning” to a debtor who had skipped town, warning him that he had better pay up, or the next letter would be to the authorities of his new town.
By far the funniest was by a young woman who was complaining to her mother that, “Men are no good. They only want one thing, and at the mere mention of marriage they take off.”
Thanks y. The tablet archives which were preserved were baked by fire when the sites were burned by invading armies (or maybe someone fell asleep and the hearth got out of control, but I doubt that). The Sumerian city of Kish was burned by a rival town and lucky us, because that was one of (if not the) largest archives of cuneiform ever found. Hattusas was burned, preserving its archive. One of the Amarna tablets evidently alludes to the destruction of Hattusas, the queen of H writing that the pharaoh should take a flying leap regarding his request for gifts.