The Duchy of Poland was a duchy in Central Europe with its capital being Gniezno. Its government system was patrimonial monarchy. The state was formed around 960. Mieszko I was crowned as the ruler of Polans between 950 and 960. The state took Christianity as its state religion in 966 durimng Christianization of Poland. The state existed until the coronation of Bolesław I the Brave for the king in 1025, who turned the duchy into the Kingdom of Poland.