Traianus belonged to a branch of the gens Ulpia, which originally came from the Umbrian city of Tuder, but he was born and raised in the Roman colony of Italica, north of modern Santiponce and northwest of Seville, in the Roman Province of Hispania Baetica.

[2] The town was founded in 206 BC by Scipio Africanus, as a settlement for wounded and invalid veterans of the wars against Carthage.

His sister Ulpia was the mother of Publius Aelius Hadrianus Afer, and grandmother of the emperor Hadrian.

After his accession to the Empire, Vespasian recognized Traianus' military successes by awarding him the governorship of Cappadocia, and naming him consul suffectus for the months of September and October in AD 72.

[7] In AD 100, his son founded a colony in North Africa, named Colonia Marciana Ulpia Trajana Thamugadi after his mother and father; today the town is known as Timgad, in Algeria.