Severus devotes the following year to suppressing Mesopotamia and other Parthian vassals who had backed Niger.

Northern Mesopotamia, including Osroene, had come again under Roman control in the expedition of Lucius Verus in 161–166, but had not been formally organized into provinces; instead, they had been left under local vassal rulers, although Roman garrisons have been maintained, notably at Nisibis.

This control is threatened in 195, during the civil war between Severus and Niger, when rebellions break out in the area, and Nisibis is besieged.

Severus quickly restores order and organizes Osroene as a full province.