The traditional version of Roman history, which has come down to us principally through Livy (64 or 59 BC – AD 12 or 17), Plutarch (46–120), and Dionysius of Halicarnassus ( 60 BC – after 7 BC), recounts that a series of seven kings ruled the settlement in Rome's first centuries. The traditional chronology, as codified by Varro (116 BC – 27 BC) and Fabius Pictor (c. 270 – c. 200 BC), allows 243 years for their combined reigns, an average of almost 35 years. Since the work of Barthold Georg Niebuhr, modern scholarship has generally discounted this schema. The Gauls destroyed many of Rome's historical records when they sacked the city after the Battle of the Allia in 390 BC (according to Varro; according to Polybius, the battle occurred in 387/6), and what remained eventually fell prey to time or to theft. With no contemporary records of the kingdom surviving, all accounts of the Roman kings must be carefully questioned.