A Brief History of the Roman Empire

Provinces with legions were almost always imperial, while ungarrisoned provinces were usually senatorial. According to the settlement, the sitting princeps technically held proconsular authority over all his provinces and was thus merely appointing men to govern in his name. Within this system, the provinces were further divided into order of importance, between major proconsular territories, minor propratorial territories and really minor procuratorial territories. The remaining procuratorial provinces were all imperial and were unique in thet equites qualified to act as governor. These, as you can imagine, wound up being the really minor, really out of the way provinces. Think mauritania.