Internal evidence suggests that Livy began to write his History of Rome in or shortly before 29 B.C. by which time Octavian, the later Augustus, had restored peace and a measure of stability to the Roman world. A note in the periocha of Book 121 records that that book (and presumably those which followed) was published (editus) after Augustus' death in A.D. 14. The implication is that the last twenty books dealing with the events from the Battle of Actium until 9 B.C. were an afterthought to the original plan and may also have been too politically controversial to be published in Augustus' lifetime.

The sheer scope of the undertaking is formidable, presupposing, as it does, the composition of three books a year on average. The introductions, especially to Books 6, 21 and 31, show that Livy began by composing and publishing in units of five books, the length of which was determined by the size of the ancient papyrus roll. As his material became more complex, this symmetrical pattern is less self-evident but it is likely that he maintained it.