The Duchy of Prussia was a historical territory located in northeastern Europe, established in 1525. It originated from the Teutonic Knights and became a duchy when the Grand Master of the order, Albert of Hohenzollern, converted to Lutheranism and secularized the territory. The duchy was a vassal state of the Kingdom of Poland. In 1701, the Duchy of Prussia was elevated to a kingdom, becoming the Kingdom of Prussia. This transition marked a significant shift in power dynamics in Europe, as the kingdom played a crucial role in the unification of Germany in the 19th century. The duchy itself was an important center for trade and culture during its existence.