He was born (year unknown) in the Roman colony of Poetovio (modern Ptuj, in Slovenia), where his father, also called Marcus Valerius Maximianus, was a local censor and priest.
Narodil sa v neznámom roku v rímskej osade Poetovio (dnešný Ptuj v Slovinsku), kde jeho otec, ktorý sa takisto volal Marcus Valerius Maximianus, pracoval ako cenzor a kňaz.