Hadrian has grown so frustrated with the continual problems in the territories north of the Danube that the new emperor contemplates withdrawing from Dacia.

As an emergency measure, Hadrian dismantles the wooden superstructure of Apollodorus’s bridge across the Danube, concerned about the threat posed by barbarian incursions across the Olt River and a southward push between a number of Trajan’s colonia and the castrum at Bersobis.

By 118, Hadrian himself has taken to the field against the Roxolani and the Iazyges, and although he defeats them, he agrees to reinstate the subsidies to the Roxolani Hadrian then decides to abandon certain portions of Trajan's Dacian conquests.

The territories added to Moesia Inferior (Southern Moldova, the southeastern edge of the Carpathian Mountains, and the plains of Muntenia and Oltenia) are returned to the Roxolani.

As a result, Moesia Inferior reverts once again to the original boundaries it had possessed prior to the acquisition of Dacia.

The portions of Moesia Inferior to the north of the Danube are split off and refashioned into a new province called Dacia Inferior, corresponding to the region of present Wallachia.

Trajan’s original province of Dacia is relabeled Dacia Superior, corresponding roughly to Transylvania.

It is at this time that Hadrian moves the Legio IV Flavia Felix from its base at Ulpia Traiana Sarmizegetusa, and orders it stationed in Moesia Superior.

A portion of the native people of the new Assyrian province had begun to adopt Christianity by Trajan's time, and still retain eastern Aramaic as a spoken and literary tongue, as they do to this day.

After Trajan’s death in 117, his successor, Hadrian, implements a new policy with respect to the recently acquired territories in the east.

Believing that the empire is overextended, Hadrian wants to retract Roman rule to more easily defensible borders.

As a result, Hadrian evacuates Trajan's three new provinces in 118.

Parthamaspates, after his defeat in Parthia, again flees to the Romans who then, as a consolation, grant him the co-rule of a restored Osroene, where he will reign together with Yalur from 118 to 122, and afterwards as sole ruler to 123.

For a century, Osroene will retain a precarious independence as a buffer state, sandwiched between the two empires.

Hadrian had not at first gone to Rome—he was busy sorting out the East and suppressing the Jewish revolt that had broken out under Trajan, then moving on to sort out the Danube frontier.

Instead, Attianus, Hadrian's former guardian, had been put in charge in Rome.

Here he "discovers" a conspiracy involving four leading Senators, including Lusius Quietus, and demands of the Senate their deaths.

There is no question of a trial—they are hunted down and killed out of hand in the summer of 118.

Because Hadrian is not in Rome at the time, he is able to claim that Attianus had acted on his own initiative.

A new crisis occurs at the beginning of Hadrian's reign (117 CE): a rising in the north, thought to have involved the Brigantes and Selgovae, Brythonic tribes of northern Britannia and southern Caledonia, although it may have resulted from foreign invasion, which is suppressed by Quintus Pompeius Falco, who governs Britannia between 118 and 122.

An inscription from Jarrow and commemorative coins issued in 119 attest to his supposed success, although a reference by the orator Fronto to many soldiers being killed in Britannia under Hadrian's rule has been suggested as indicating that the victory was hard-won.

Fronto may have been referring to a different conflict at another time, however.

Emperor Ān had in 120 named his only son, Prince Bǎo, crown prince.

Empress Dowager Deng dies in 121, and An, at the age of 27, finally has the reins of the imperial administration.

He posthumously honores his father Prince Qing as Emperor Xiaode and his mother Consort Zuǒ as Empress Xiaode; his paternal grandmother Consort Song as Empress Jingyin; and his stepmother Consort Gěng with the unique title of "Grand Consort of Gānlíng" (Gānlíng being Prince Qing's tomb) -- a title inferior to his mother's, even though Consort Gěng was his father's wife.

He, however, was close to her and her brother Gěng Bǎo, and he quickly makes his stepuncle a powerful official in his administration.

Initially, Ān continued to follow the Empress Dowager's policies, including leaving members of her clan in important advisorial positions.

However, his own close circle of associates, including Jiang, Li, Wang, and Empress Yan, are ready to act.

Late in 121, he strips members of the Deng clan of their posts and fiefs, and many of them commit suicide, probably under duress.

Later, he relents and allows some of the survivors to return, but by that time the Deng clan has been decimated.

In 121, there are again Qiang and Xianbei rebellions, which will continue to plague the emperor for the rest of his reign.

The Song clan of Emperor Ān's grandmother has become honored in the place of the Dengs, but the clan of the empress, the Yáns—particularly Empress Yán's brothers Yán Xiǎn, Yán Jǐng, and Yán Yào—wieldi much more actual power.

Also powerful are the eunuchs Jiang and Li, who are created marquesses.

They, along with several other eunuchs, as well as Wang and her daughter Bó Róng, have become extremely corrupt in their ways, without any punishment from Emperor Ān, who ignores all criticism of these individuals.

The emperor often listens to their suggestions, while ignoring the advice of his key officials.

One of the most outspoken of these is Yáng Zhèn, the commander of the armed forces, who will eventually be removed from his post in 124 and commit suicide in protest.

The reign of Hadrian, despite his own great reputation as a military administrator, will be marked by a general lack of major military conflicts, apart from the Second Roman-Jewish War.

He has surrendered Trajan's conquests in Mesopotamia, considering them to be indefensible.

There is almost a war with Parthia around 121, but the threat is averted when Hadrian succeeds in negotiating a peace.

Around this time, Suetonius publishes his highly readable combination of fact and unverifiable rumor, Lives of the Caesars, an often scandalous account of the histories of Julius Caesar and of Rome's first eleven emperors, from Augustus to Domitian.

The Roman settlement at present Wiesbaden is first mentioned in 121 using the name Aquae Mattiacorum (Latin for "Waters of the Mattiaci").

The Mattiaci are a Germanic tribe, possibly a branch of the neighboring Chatti, who live in the vicinity at this time.

The town also appears as Mattiacum in Ptolemy's Geographia (2.10).

The line of Roman frontier fortifications, the Limes Germanicus, is constructed in the Taunus not far north of Wiesbaden.

Just over the Rhine, connected by a bridge at the present-day borough of Mainz-Kastel (Roman "castellum"), a strongly fortified bridgehead, is …

…the capital of the province of Germania Superior, Moguntiacum (present-day Mainz), which serves as base of two (at times three) Roman legions.