March of Gero

The Marca Geronis or March of Gero is a historiographical term, derived from titles and offices of early medieval military commanders and governors of various German frontier jurisdictions in lands of Polabian Slavs. In primary sources, such as the Thietmar's Chronicle, the term was used in relation to count Gero II (d. 1015), whose frontier province (march) was mentioned as the count Gero’s march (Latin: Geronis marcham comitis; German: Mark des Grafen Gero). In later historiography, the same term was borrowed and reapplied as a descriptive designation for an earlier frontier jurisdiction of count Gero I (d. 965), a prominent noble from the Duchy of Saxony, who was appointed margrave (Latin: marchio) by king and emperor Otto I (936-973). The nature and scope of his jurisdiction as a margrave is indicated in several sources, such as the 11th century Thietmar's Chronicle, that mentions Gero I as Margrave of the East (Latin: Gero Orientalium marchio; German: Markgraf Gero von der Ostmark).