In central Europe, specifically the Frankish/German/Holy Roman Empire of Charlemagne, raids and wars to the east generated a steady supply of slaves from the Slavic captives of these regions. Because of high demand for slaves in the wealthy Muslim empires of Northern Africa, Spain, and the Near East, especially for slaves of European descent, a market for these slaves rapidly emerged. So lucrative was this market that it spawned an economic boom in central and western Europe, today known as the Carolingian Renaissance. This boom period for slaves stretched from the early Muslim conquests to the High Middle Ages but declined in the later Middle Ages as the Islamic Golden Age waned.