Hispania Tarraconensis in the context of "Otho"

Trajan (/ˈtreɪdʒən/ TRAY-jən; born Marcus Ulpius Traianus, 18 September 53 – c. 9 August 117) was a Roman emperor from AD 98 to 117, remembered as the second of the Five Good Emperors of the Nerva–Antonine dynasty. He was a philanthropic ruler and a successful soldier-emperor who presided over one of the greatest military expansions in Roman history, during which, by the time of his death, the Roman Empire reached its maximum territorial extent. He was given the title of Optimus ('the best') by the Roman Senate.

Trajan was born in the municipium of Italica in the present-day Andalusian province of Seville in southern Spain, an Italic settlement in Hispania Baetica; his gens Ulpia came from the town of Tuder in the Umbria region of central Italy. His namesake father, Marcus Ulpius Traianus, was a general and distinguished senator. Trajan rose to prominence during the reign of Domitian; in AD 89, serving as a legatus legionis in Hispania Tarraconensis, he supported the emperor against a revolt on the Rhine led by Antonius Saturninus. He then served as governor of Germania and Pannonia. In September 96, Domitian was succeeded by the elderly and childless Nerva, who proved to be unpopular with the army. After a revolt by members of the Praetorian Guard, Nerva decided to adopt as his heir and successor the more popular Trajan, who had distinguished himself in military campaigns against Germanic tribes.

Hispania was the Roman name for the Iberian Peninsula. Under the Roman Republic, it was divided into two provinces: Hispania Citerior and Hispania Ulterior. During the Roman Empire, under the Principate, Hispania Ulterior was subdivided into Baetica and Lusitania, while Hispania Citerior was reorganized as Hispania Tarraconensis.

Beginning with Diocletian’s Tetrarchy (AD 293), the territory of Tarraconensis was further divided to create the provinces of Carthaginensis and Gallaecia (also called Callaecia, the origin of the name of modern Galicia). All the Hispanic provinces on the mainland, together with the Balearic Islands and the North African province of Mauretania Tingitana, were later organized into the Diocesis Hispaniarum, governed by a vicarius.

Hispania Baetica, often abbreviated Baetica, was one of three Roman provinces created in Hispania (the Iberian Peninsula) in 27 BC. Baetica was bordered to the west by Lusitania, and to the northeast by Tarraconensis. Baetica remained one of the basic divisions of Hispania under the Visigoths. Its territory approximately corresponds to modern Andalusia.

Gallia Aquitania (/ˈɡæliə ˌækwɪˈteɪniə/, Latin: [ˈɡalːi.a akᶣiːˈtaːni.a]), also known as Aquitaine or Aquitaine Gaul, was a province of the Roman Empire. It lies in present-day southwest France and the comarca of Val d'Aran in northeast Spain, where it gives its name to the modern region of Aquitaine. It was bordered by the provinces of Gallia Lugdunensis, Gallia Narbonensis, and Hispania Tarraconensis.

Hispania Citerior (English: "Hither Iberia", or "Nearer Iberia") was a Roman province in Hispania during the Roman Republic. It was on the eastern coast of Iberia down to the town of Cartago Nova, today's Cartagena in the autonomous community of Murcia, Spain. It roughly covered today's Spanish autonomous communities of Catalonia and Valencia. Further south was the Roman province of Hispania Ulterior ("Further Spain" or "Further Iberia"), named as such because it was further away from Rome.

The two provinces were established in 197 BC, four years after the end of the Second Punic War (218–201 BC). During this war Scipio Africanus defeated the Carthaginians at the Battle of Ilipa (near Seville) in 206 BC. This led to the Romans taking over the Carthaginian possessions in southern Spain and on the east coast up to the River Ebro. Several governors of Hispania Citerior commanded wars against the Celtiberians who lived to the west of this province. In the late first century BC Augustus reorganised the Roman provinces in Hispania. Hispania Citerior was replaced by the larger province of Hispania Tarraconensis, which included the territories the Romans had subsequently conquered in central, northern and north-western Hispania. Augustus also renamed Hispania Ulterior as Hispania Baetica and created a third province, Hispania Lusitania.