Soon after assuming the Italian throne, Berengar II reorganised his territories south of the Po River, dividing them into three new marches (frontier districts) named after their respective margraves: the marca Aleramica of Aleram of Montferrat, the marca Arduinica of Arduin Glaber, and the marca Obertenga of Oberto. This last division consisted of eastern Liguria and was also known as the marca Januensis or March of Genoa. It consisted of Tuscany with the cities of Genoa, Luni, Tortona, Parma, and Piacenza.
In 960, he had to take refuge in Germany. The next year, Pope John XII asked Otto I of Germany to intervene in Italy to protect him from Berengar. When Otto took control of Italy, Oberto was able to return to his lands, with the title of count palatine confirmed by Otto.