Here's why:
* Limited Record Keeping: Record keeping in the 4th century was far less advanced than it is today. Accurate birth records for common people were rare.
* Focus on Emperors and Elites: The records that did exist tended to focus on emperors, religious figures, and other powerful individuals.
* Dating Inaccuracies: Even for significant figures, dating in that era was often imprecise.
Therefore, we cannot say with any certainty who, if anyone, was born in 345 AD.