Archaeological evidence shows that in the 5th century BC, there was an economic downturn that would have precluded considerable population growth. The territory of Rome had increased by 75% by the early 4th century, but the bulk of the increase was caused by the recent conquest of the city of Veii and its territory, and its population did not have Roman citizenship, a requirement to serve in the Roman army. Such considerations make it unlikely that the size of the population of Roman citizens would have been large enough to provide a military pool of 24,000 or more soldiers at the time of the Battle of the Allia.