The Duchy of Holstein was a historical region located in northern Germany, primarily within the modern state of Schleswig-Holstein. It was part of the larger Duchy of Schleswig and was ruled by various noble families, including the House of Oldenburg. The duchy played a significant role in the political landscape of northern Europe during the Middle Ages and the early modern period. Holstein's strategic location made it a point of contention between Denmark and Germany. The duchy was involved in several conflicts, including the Danish Wars, which shaped its borders and governance. Ultimately, it became part of the German Empire in the 19th century, marking the end of its status as an independent duchy.