What frontier zone did Charlemagne establish south of the Pyrenees?

The frontier zone Charlemagne established south of the Pyrenees was the Spanish March, also called the Hispanic March. It was a military and political buffer intended to protect the southern edge of the Carolingian Empire from the Umayyad Emirate of Córdoba in al-Andalus.

The march took shape around 795 in the eastern Pyrenees, after earlier Frankish campaigns had extended influence across parts of the region. It was not a single tightly organized province in the modern sense. Instead, it consisted of counties and lordships governed by counts who owed allegiance to the Frankish ruler. These territories included areas that later became closely associated with Catalonia and other northeastern Iberian regions.

A common mix-up is to treat the Spanish March as identical to all Christian territory south of the Pyrenees. Frankish control was uneven, and several local rulers retained substantial autonomy. Barcelona was captured by Frankish forces in 801, strengthening the march's strategic position.

After Charlemagne's death in 814, revolts and military setbacks weakened Carolingian control. Pamplona broke away in 816, and the County of Aragon followed in 820. Other counties gradually developed greater independence.