Paristrion (meaning "beside the Ister"), or Paradounabon/Paradounabis, which is preferred in official documents, is an East Roman (Byzantine) province covering the southern bank of the Lower Danube (Moesia Inferior) in the eleventh and twelfth centuries.Although Byzantine authors use the term to describe the lands along the Danube in general, the province of Paristrion seems to have comprised mostly modern Dobruja.

It is not certain exactly when the province was established: the Romanian scholar Nicolae Bănescu considered that it was established immediately after the end of the Rus'–Byzantine War of 970–971, while others, such as Vasil Zlatarski, thought it a later, mid-eleventh century creation.

It is governed by a katepano or a doux, and is probably based at Dorostolon/Durostorum (modern Silistra), where a Byzantine strategia ("generalcy") is indeed attested in the 970s.

In the aftermath of his victory over the Rus', Emperor John I Tzimiskes (r. 969–976) appoints general Leo Sarakenopoulos as commander over northeastern Bulgaria, based at Pereyaslavets/Ioannopolis.

Sarakenopoulos and his subordinates engage in major fortification activities in the region of the Dobruja over the next few years, where abandoned Roman-era forts are rebuilt and reoccupied.The region however falls back under Bulgarian control under the Cometopuli brothers in 986 and is held until c. 1001, when Byzantine control is reestablished.

(Bănescu, however, considered that Dorostolon at least remained in Byzantine hands throughout.

From the 1030s on, the region faces the continuous raids of the Pechenegs.)

The population is withdrawn to a few large fortified centers, and the Pechenegs are allowed to settle in the province as allies and colonists (termed mixobarbaroi by contemporary authors) and kept pacified through subsidies and through a vibrant trade.

It is not until the early 1070s that the Pechenegs launch an open rebellion, and pose a constant threat to the Empire's Balkan provinces until decisively defeated at the Battle of Levounion in 1091.

Despite occasional Cuman raids thereafter, the Paristrion remains largely peaceful and prosperous in the twelfth century.

The province seems to have been disbanded by the late twelfth century.