RESTITVT ORIENTIS. Which Roman emperor restored the Orient (the Roman East)?
Why did it need restoring?
In the third and fourth centuries the Romans fought the Sasanians (Persians) for control of the East (Orient, in Roman terms). Sometimes Roman provincial cities including Nisibis and Singara in upper Mesopotamia were temporarily conquered by the Persians. Then a major Roman campaign would be mounted to attempt to return the region to Roman control. One such successful campaign was under Gordian III (238-244).
To the right. A large (32 mm) sestertius-sized coin of Gordian III and his wife, Tranquillina, from Nisibis ("NЄCIBI" from 1:30 to 4:00 on the reverse), with the city goddess Tyche seated on rocks with a river god swimming left below (at 7:00) and a tiny ram jumping left, head back, above her turreted headdress.
Gordian III recaptured Carrhae, Hatra, Nisibis, and the rest of Roman Mesopotamia. Gordian III was only 19 and clearly not the mastermind. Really the successes belonged to his Praetorian Prefect and father-in-law, Timesitheus, who died from illness, possibly aided by Philip, who replaced him. Then Gordian III died while still in Mesopotamia because of the treachery of Philip. Philip inherited the throne. In order to withdraw the troops safely, Philip (244-249) had to make peace with the Persians (Sasanians) at the cost of 500,000 denarii. Nevertheless, he issued coins claiming success.
To the right. A 24 mm silver "antoninianus" of Philip with reverse PAX FVNDATA CVM PERSIS "Peace founded with Persia". Pax standing holding up olive branch.
Roman control did not last long. Upper Mesopotamia was recaptured by the Sasanians, c. 250-252, which explains the lack of later Roman provincial coins from the cities of Mesopotamia.
So, which emperor reconquered the Orient?
Valerian (253-260) took on the task of reconquering the Roman East. Our sources are unclear about whether he had just the one disastrous campaign which lead to his capture, or two campaigns, the first one successful which was undone upon withdrawal and therefore required a second. Regardless, Valerian issued coins claiming RESTITVT ORIENTIS. If there were two campaigns, the coins may be honestly reporting on the success of the first campaign. Or, if there was only one campaign, they may be premature propaganda reporting an anticipated success which didn't happen.
The East was recaptured from the Sasanians by Odaenathus of Palmyra late in the time of Gallienus. Aurelian recovered it for the central empire by defeating Palmyra. So, for Aurelian coins with RESTITVT ORIENTIS are justified. He issued two designs.
Aurelian, 270-275
21-19 mm. 3.53 grams.
RESTITVT ORIENTIS
The same design as above under Valerian.
RIC 234. Sear III 11595.
Gratian (367-389)
AE2. 23 mm. 4.23 grams.
RIC Siscia 26b2
Emperor and kneeling figure in a pose similar to that above. This time the emperor is crowned by Victory on a globe he is holding out in his left hand.
REPARATIO REIPVB. He is repairing/restoring the republic. (Ha!) Perhaps the lady is kissing his hand in gratitude. Maybe he is about to raise her up. Note the turreted crown on the woman. On this coin it seems that Victory (Crowning the emperor) makes the event happen (which event if any, is uncertain). Surely victory in the east made the event on Aurelian's coin happen, too. This is not an entreaty by the kneeling figure. It is a "Thank you!"
Conclusion. Aurelian restored the East and celebrated it with RESTITVT ORIENTIS types.