Decades: 200s 210s 220s 230s 240s - 250s - 260s 270s 280s 290s 300s
Years: 245 246 247 248 249 - 250 - 251 252 253 254 255
Diophantus writes Arithmetica the first systematic treatise on algebra.
A group of Franks penetrate as far as Tarragona in Spain (approximate date).
Goths invade Moesia.
The Alamanni drive the Romans from the modern area of Donau-Ries.
Decius begins a period of persecution of the Christians in the Roman Empire.
Maximian, Roman emperor (approximate date)
Constantius Chlorus, Roman emperor and father of Constantine the Great (approximate date)
Licinius, Roman emperor (approximate date)
Arius, Christian priest and namesake of Arianism
January 20 - Pope Fabian
Ambrose of Alexandria, Christian writer (approximate date)
Denis, Christian saint\n