Etymologically, the word "margrave" (Latin: marchio, c. 1551) is the English and French form of the German noble title Markgraf (Mark, meaning "march" or "mark", that is, border land, added to Graf, meaning "Count"); it is related semantically to the English title "Marcher Lord". As a noun and hereditary title, "margrave" was common among the languages of Europe, such as Spanish and Polish.
A Markgraf (margrave) originally functioned as the military governor of a Carolingian march, a medieval border province. Because the territorial integrity of the borders of the realm of a king or emperor was essential to national security, the vassal (whether a count or other lord) whose lands were on the march of the kingdom or empire was likely to be appointed a margrave and given greater responsibility for securing the border.
The greater exposure of a border province to military invasion mandated that the margrave be provided with military forces and autonomy of action (political as well as military) greater than those accorded other lords of the realm. As a military governor, the margrave's authority often extended over a territory larger than the province proper, because of border expansion subsequent to royal wars.
The margrave thus usually came to exercise commensurately greater politico-military power than other noblemen. The margrave maintained the greater armed forces and fortifications required for repelling invasion, which increased his political strength and independence relative to the monarch. Moreover, a margrave might expand his sovereign's realm by conquering additional territory, sometimes more than he might retain as a personal domain, thus allowing him to endow his own vassals with lands and resources in return for their loyalty to him; the consequent wealth and power might allow the establishment of a de facto near-independent principality of his own.
Most marches and their margraves arose along the eastern borders of the Carolingian Empire and the successor Holy Roman Empire. The Breton Mark on the Atlantic Ocean and the border of peninsular Brittany and the Marca Hispanica on the Muslim frontier (including Catalonia) are notable exceptions. The Spanish March was most important during the early stages of the peninsular Reconquista of Iberia: ambitious margraves based in the Pyrenees took advantage of disarray in Muslim Al-Andalus to extend their territories southward, leading to the establishment of the Christian kingdoms that would become unified Spain in the fifteenth century. The Crusaders created new and perilous borders susceptible to holy war against the Saracens; they thus had use for such border marches as the Greek Margraviate of Bodonitsa (1204–1414).
As territorial borders stabilised in the late Middle Ages, marches began to lose their primary military importance; but the entrenched families who held the office of margrave gradually converted their marches into hereditary fiefs, comparable in all but name to duchies. In an evolution similar to the rises of dukes, landgraves, counts palatine, and Fürsten (ruling princes), these margraves became substantially independent rulers of states under the nominal overlordship of the Holy Roman Emperor.
Holy Roman Emperor Charles IV's Golden Bull of 1356 recognized the Margrave of Brandenburg as an elector of the Empire. Possession of an electorate carried membership in the highest "college" within the Imperial Diet, the main prerogative of which was the right to elect, along with a few other powerful princes and prelates, the non-hereditary Emperor whenever death or abdication created a vacancy on the Imperial throne. Mark Brandenburg became the nucleus of the House of Hohenzollern's later Kingdom of Prussia and the springboard to their eventual accession as German Emperors in 1871.
Another original march also developed into one of the most powerful states in Central Europe: the Margraviate of Austria. Its rulers, the House of Habsburg, rose to obtain a de facto monopoly on election to the throne of the Holy Roman Empire. They also inherited several, mainly Eastern European and Burgundian, principalities. Austria was originally called Marchia Orientalis in Latin, the "eastern borderland", as (originally roughly the present Lower-) Austria formed the easternmost reach of the Holy Roman Empire, extending to the lands of the Magyars and the Slavs (since the 19th century, Marchia Orientalis has been translated as Ostmark by some Germanophones, though medieval documents attest only to the vernacular name Ostarrîchi). Another march in the south-east, Styria, still appears as Steiermark in German today.
The margraves of Brandenburg and of Meissen eventually became, respectively, the kings of (originally 'in') Prussia and of Saxony.