The south-western part of Dacia (modern Romania) becomes a Roman province: Roman Dacia.
Roman Dacia ( DAY-sh; also known as Dacia Traiana, "Trajan Dacia", or Dacia Felix, "Fertile/Happy Dacia") was a province of the Roman Empire from 106 to 271275 AD. Its territory consisted of what are now the regions of Oltenia, Transylvania and Banat (today all in Romania, except the last one which is split between Romania, Hungary, and Serbia). During Roman rule, it was organized as an imperial province on the borders of the empire. It is estimated that the population of Roman Dacia ranged from 650,000 to 1,200,000. It was conquered by Trajan (98117) after two campaigns that devastated the Dacian Kingdom of Decebalus. However, the Romans did not occupy its entirety; Criana, Maramure, and most of Moldavia remained under the Free Dacians.
After its integration into the empire, Roman Dacia saw constant administrative division. In 119, it was divided into two departments: Dacia Superior ("Upper Dacia") and Dacia Inferior ("Lower Dacia"; later named Dacia Malvensis). Between 124 and around 158, Dacia Superior was divided into two provinces, Dacia Apulensis and Dacia Porolissensis. The three provinces would later be unified in 166 and be known as Tres Daciae ("Three Dacias") due to the ongoing Marcomannic Wars. The area was the focus of a massive Roman colonization. New mines were opened and ore extraction intensified, while agriculture, stock breeding, and commerce flourished in the province. Roman Dacia was of great importance to the military stationed throughout the Balkans and became an urban province, with about ten cities known and all of them originating from old military camps. Eight of these held the highest rank of colonia. Ulpia Traiana Sarmizegetusa was the financial, religious, and legislative center and where the imperial procurator (finance officer) had his seat, while Apulum was Roman Dacia's military center.
From its creation, Roman Dacia suffered great political and military threats. The Free Dacians, allied with the Sarmatians, made constant raids in the province. These were followed by the Carpi (a Dacian tribe) and the newly arrived Germanic tribes (Goths, Taifali, Heruli, and Bastarnae) allied with them. All this made the province difficult for the Roman emperors to maintain, already being virtually lost during the reign of Gallienus (253268). Aurelian (270275) would formally relinquish Roman Dacia in 271 or 275 AD. He evacuated his troops and civilian administration from Dacia, and founded Dacia Aureliana with its capital at Serdica in Lower Moesia. The Romanized population still left was abandoned, and its fate after the Roman withdrawal is controversial. According to one theory, the Latin spoken in Dacia, mostly in modern Romania, became the Romanian language, making the Romanians descendants of the Daco-Romans (the Romanized population of Dacia). The opposing theory states that the origin of the Romanians actually lies on the Balkan Peninsula.
Dacia (, DAY-shə; Latin: [ˈd̪aːkija]) was the land inhabited by the Dacians. The Greeks referred to them as the Getae (east of Dacia) and the Romans called them Daci.
Dacia was bounded in the south approximately by the Danubius river (Danube), in Greek sources the Istros, or at its greatest extent, by the Haemus Mons. Lower Moesia (Dobruja), a region south-east of the Danube, was a core area where the Getae lived and interacted with the Ancient Greeks. In the east it was bounded by the Pontus Euxinus (Black Sea) and the river Danastris (Dniester), in Greek sources the Tyras. But several Dacian settlements are recorded between the rivers Dniester and Hypanis (Southern Bug), and the Tisia (Tisza) to the west.
At times Dacia included areas between the Tisa and the Middle Danube. The Carpathian Mountains are located in the middle of Dacia. It thus corresponds to the present-day countries of Romania and Moldova, as well as smaller parts of Bulgaria, Serbia, Hungary, Poland, Slovakia, and Ukraine.
A Dacian Kingdom of variable size existed between 82 BC until the Roman conquest in AD 106. The capital of Dacia, Sarmizegetusa, located in modern Romania, was destroyed by the Romans, but its name was added to that of the new city (Ulpia Traiana Sarmizegetusa) built by the latter to serve as the capital of the Roman province of Dacia.