I'm currently reading Thucydides' History of the Peloponnesian War, and despite nearing the end of the book, this question now popped into my head. In an age before the printing press or even the codex form of books, how would ancient peoples, particularly in Ancient Greece and Ancient Rome go about publishing their works? More than that, how would they distribute those books?

In Thucydides' case, one thing that really stands out to me is that the book ends mid sentence in 411 BC, following the Athenian victory at Cynossema. This is despite the fact that Thucydides stated that he would cover the Peloponnesian War in its entirety while the war itself lasted until 404 BC. However, Xenophon, in his Hellenika, starts literally right where Thucydides left off. So that alone tells me that Thucydides's work would have been in distribution in some form, such that Xenophon would have known where it ended and where to pick up from (granted, there are some assumptions being made here).

So yeah, to summarize, how would Ancient Greek and Roman writers publish their works and then distribute them to the wider population?