Although several Roman sources including Livy and Polybius talk extensively about the Roman army of the Roman Kingdom period that followed the Etruscan capture of the city, no contemporary accounts survive. Polybius, for example, wrote some 300 years after the events in question, and Livy some 500 years later. Additionally, what records were kept by the Romans at this time were later destroyed when the city was sacked. The sources for this period cannot therefore be seen as reliable, as they can be for later military history, e.g. from the First Punic War onwards.