According to the information collected from Latin and Greek sources, the first clash between the "newborn Sasanian power" in its west borders with Rome occurred by the Persians' attack on the regions held by Rome in Northern Mesopotamia on Ardashir's era, 230. Ardashir besieged Nusaybin, which was one of the two fortresses of Roman defense system in Mesopotamia -the other being Harran, but was not able to take it; the Sasanian riders' assault was pulled to other Syrian regions and Cappadocia and they invaded it. After the Romans' unfruitful attempt to make peace with Ardashir, Severus Alexander eventually decided to oppose the Persians unwillingly and reluctantly in 232. The Roman forces led by Alexander attacked Armenia by one military column and the south by two columns. Although there is no accurate information about the details of the events, it is known that the Romans achieved some victories in the north (Armenia); but the troops sent to Southern Mesopotamia did not achieve anything due to the natural difficulties. Anyway, Ardashir's invasion was repelled by Rome.