The paper presents the archaeological facts from the north-west of Dacia, the extend of the Dacian inhabitance, based on known discoveries, especially on the pre-Roman Dacian settlements and fortifications identified and mapped within this area (Arad, Bihor, Sălaj, Baia Mare, the historical Maramureş-Ukraina), dating from the beginning of the second century AD. Basing on the Romanian specialists' thesis, which limit Decebalus' kingdom on the line of these fortifications: Cliţ, Şuşturogi, Săcălăsău, Tăşad, Marca, Şimleu Silvaniei, Oarţa de Sus, Slatina-Solotvino and Malaia Kopania from the historical Maramureş, beyond the Tisa river (from Ukraina), it may be observed the arrangement of the today known limes on the alignment of the Meseş Mountain, that Emperor Trajan did not incorporate this space to the newly created Roman province Dacia, organized in 106 A.D.
The ancient literary sources (Cassius Dio) remind about an area demanded by the Sarmatians after the Dacian wars, as a part of an initial support agreement of the Roman forces against Decebalus, area incorporated by Trajan in the recently created Roman province Dacia.
At Supurul de Sus, Satu Mare County, on the "Dealul Şoarecelui" and "Dealul Soldubiţa" plateau, in the spots known as "La Şanţ" and "Bondaua", it has been identified and investigated a Roman linear earth fortifications system consisting of ditches, ramparts and earth fortifications attached to this defensive system, identified up to present on a length of approximately 3.5 km, which, due to it's arrangement, blocked the large valley of Crasna, the only access way towards Porolissum, to roman Dacia. This defensive system has been identified in Barbaricum, at approximately 50 km west from the military complex of Porolissum. The present paper will refer to this Roman defensive system, trying to convey the archaeological, historical, geographical and literary arguments regarding the extend up to the area of Criş and Tisa (Hungary) rivers of Roman province Dacia, organized by Emperor Trajan even since 106 AD.