The March of Styria, originally known as Carantanian march, was a southeastern frontier march of the Holy Roman Empire. It was broken off the larger March of Carinthia, itself a march of the Duchy of Bavaria, around 970 as a buffer zone against the Hungarian invasions. Under the overlordship of the Carinthian dukes from 976 onwards, the territory evolved to be called Styria, so named for the town of Steyr, then the residence of the Otakar margraves. It became an Imperial State in its own right, when the Otakars were elevated to Dukes of Styria in 1180.

The March of Carinthia was a frontier district (march) of the Carolingian Empire created in 889. Before it was a march, it had been a principality or duchy ruled by native-born Slavic princes at first independently and then under Bavarian and subsequently Frankish suzerainty. The realm was divided into counties which, after the succession of the Carinthian duke to the East Frankish throne, were united in the hands of a single authority. When the march of Carinthia was raised into a Duchy in 976, a new Carinthian march was created. It became the later March of Styria.