Palmyra became part of the Roman Empire when it was conquered and paid tribute early in the reign of Tiberius, around 14 AD.
The Romans included Palmyra in the province of Syria, and defined the region's boundaries.
Pliny the Elder asserted that both the Palmyrene and Emesene regions were contiguous; a marker at the Palmyrene's southwestern border was found in 1936 by Daniel Schlumberger at Qasr al-Hayr al-Gharbi, dating from the reign of Hadrian or one of his successors, which marked the boundary between the two regions.
This boundary probably ran northwards to Khirbet al-Bilaas on Jabal al-Bilas where another marker, laid by the Roman governor Silanus, has been found, 75 kilometres (47 mi) northwest of Palmyra, probably marking a boundary with the territory of Epiphania.
Meanwhile, Palmyra's eastern border extended to the Euphrates valley.
This region included numerous villages subordinate to the center, including large settlements such as al-Qaryatayn.
The Roman imperial period brought great prosperity to the city, which enjoyed a privileged status under the empire—retaining much of its internal autonomy, being ruled by a council, and incorporating many Greek city-state (polis) institutions into its government.

The earliest Palmyrene text attesting a Roman presence in the city dates to 18 AD, when the Roman general Germanicus tried to develop a friendly relationship with Parthia; he sent the Palmyrene Alexandros to Mesene, a Parthian vassal kingdom.
This was followed by the arrival of the Roman legion Legio X Fretensis the following year.
Roman authority was minimal during the first century AD, although tax collectors were resident, and a road connecting Palmyra and Sura was built in AD 75.
The Romans used Palmyrene soldiers, but (unlike typical Roman cities) no local magistrates or prefects are recorded in the city.
Palmyra saw intensive construction during the first century, including the city's first walled fortifications, and the Temple of Bel (completed and dedicated in 32 AD).
During the first century Palmyra developed from a minor desert caravan station into a leading trading center, with Palmyrene merchants establishing colonies in surrounding trade centers.

Palmyrene trade reached its acme during the second century, aided by two factors; the first was a trade route built by Palmyrenes, and protected by garrisons at major locations, including a garrison in Dura-Europos manned in 117 AD.
The second was the Roman conquest of the Nabataean capital Petra in 106, shifting control over southern trade routes of the Arabian Peninsula from the Nabataeans to Palmyra.
In 129 Palmyra was visited by Hadrian, who named it "Hadriane Palmyra" and made it a free city.
Hadrian promoted Hellenism throughout the empire, and Palmyra's urban expansion was modeled on that of Greece.
This led to new projects, including the theatre, the colonnade and the Temple of Nabu.
Roman garrisons are first attested in Palmyra in 167, when the cavalry Ala I Thracum Herculiana was moved to the city.
By the end of the second century, urban development diminished after the city's building projects peaked.

In the 190s, Palmyra was assigned to the province of Phoenice, newly created by the Severan dynasty.
Toward the end of the second century, Palmyra began a steady transition from a traditional Greek city-state to a monarchy due to the increasing militarization of the city and the deteriorating economic situation; the Severan ascension to the imperial throne in Rome played a major role in Palmyra's transition:
The Severan-led Roman–Parthian War, from 194 to 217, influenced regional security and affected the city's trade.
Bandits began attacking caravans by 199, leading Palmyra to strengthen its military presence.

The new dynasty favored the city, stationing the Cohors I Flavia Chalcidenorum garrison there by 206.
Caracalla made Palmyra a colonia between 213 and 216, replacing many Greek institutions with Roman constitutional ones.
Severus Alexander, emperor from 222 to 235, visited Palmyra in 229.
Palmyra became part of the Roman Empire when it was conquered and paid tribute early in the reign of Tiberius, around 14 AD. The Romans included Palmyra in the province of Syria, and defined the region's boundaries. Pliny the Elder asserted that both the Palmyrene and Emesene regions were contiguous; a marker at the Palmyrene's southwestern border was found in 1936 by Daniel Schlumberger at Qasr al-Hayr al-Gharbi, dating from the reign of Hadrian or one of his successors, which marked the boundary between the two regions. This boundary probably ran northwards to Khirbet al-Bilaas on Jabal al-Bilas where another marker, laid by the Roman governor Silanus, has been found, 75 kilometres (47 mi) northwest of Palmyra, probably marking a boundary with the territory of Epiphania. Meanwhile, Palmyra's eastern border extended to the Euphrates valley. This region included numerous villages subordinate to the center, including large settlements such as al-Qaryatayn. The Roman imperial period brought great prosperity to the city, which enjoyed a privileged status under the empire—retaining much of its internal autonomy, being ruled by a council, and incorporating many Greek city-state (polis) institutions into its government.
The earliest Palmyrene text attesting a Roman presence in the city dates to 18 AD, when the Roman general Germanicus tried to develop a friendly relationship with Parthia; he sent the Palmyrene Alexandros to Mesene, a Parthian vassal kingdom. This was followed by the arrival of the Roman legion Legio X Fretensis the following year. Roman authority was minimal during the first century AD, although tax collectors were resident, and a road connecting Palmyra and Sura was built in AD 75. The Romans used Palmyrene soldiers, but (unlike typical Roman cities) no local magistrates or prefects are recorded in the city. Palmyra saw intensive construction during the first century, including the city's first walled fortifications, and the Temple of Bel (completed and dedicated in 32 AD). During the first century Palmyra developed from a minor desert caravan station into a leading trading center, with Palmyrene merchants establishing colonies in surrounding trade centers.
Palmyrene trade reached its acme during the second century, aided by two factors; the first was a trade route built by Palmyrenes, and protected by garrisons at major locations, including a garrison in Dura-Europos manned in 117 AD. The second was the Roman conquest of the Nabataean capital Petra in 106, shifting control over southern trade routes of the Arabian Peninsula from the Nabataeans to Palmyra. In 129 Palmyra was visited by Hadrian, who named it "Hadriane Palmyra" and made it a free city. Hadrian promoted Hellenism throughout the empire, and Palmyra's urban expansion was modeled on that of Greece. This led to new projects, including the theatre, the colonnade and the Temple of Nabu. Roman garrisons are first attested in Palmyra in 167, when the cavalry Ala I Thracum Herculiana was moved to the city. By the end of the second century, urban development diminished after the city's building projects peaked.
In the 190s, Palmyra was assigned to the province of Phoenice, newly created by the Severan dynasty. Toward the end of the second century, Palmyra began a steady transition from a traditional Greek city-state to a monarchy due to the increasing militarization of the city and the deteriorating economic situation; the Severan ascension to the imperial throne in Rome played a major role in Palmyra's transition:
The Severan-led Roman–Parthian War, from 194 to 217, influenced regional security and affected the city's trade. Bandits began attacking caravans by 199, leading Palmyra to strengthen its military presence.
The new dynasty favored the city, stationing the Cohors I Flavia Chalcidenorum garrison there by 206. Caracalla made Palmyra a colonia between 213 and 216, replacing many Greek institutions with Roman constitutional ones. Severus Alexander, emperor from 222 to 235, visited Palmyra in 229.
Palmyra