The March of Genoa or Eastern Liguria was created in 961 by the Emperor Otto I. It was originally called either the marca Obertenga after its first holder, Oberto I, or the marca Januensis after its original capital and chief city, Genoa. Its creation was part of a general reorganisation of the northwest of Italy into three frontier districts. Western Liguria became the March of Montferrat and the interior became the March of Turin. It comprised the counties of Luni, Tortona, Milan, and Genoa.
The march was originally held in the elder line of the Obertenghi, descended from Oberto I. The title marchio became common in the family. Albert Azzo II was called marchio de L(a/o)ngobardia. By his time, the march was often called the March of Milan or Liguria. His grandson, Obizzo I, became the first Margrave of Este in 1173 and was created "Margrave of Milan and Genoa" in 1184 by the Emperor Frederick I. From thereafter, the title of Este had more importance, especially with the growth of the commune of Milan and the Republic of Genoa.