During the reign of Charles I (1866-1914), the coinage of Romania underwent significant development. From the initial chaos, when different regions minted their own money, a unified and stable monetary system gradually emerged. In 1867, the leu was introduced as the official unit of the Romanian currency. The first leut coins were made of silver and gold. Coins were minted in both bronze and copper. Paper money was put into circulation in 1870. Joining the Latin Monetary Union (1878) stabilized the value of the leu. The issuance of paper money was supervised by the Romanian National Bank (Banca Națională a României). , 10, 20, 50 and 100 leu. I. Many commemorative coins were minted during Károly's reign. These coins commemorated important historical events and persons. The most common commemorative coins depicted the portrait of the king. I. King Charles' coinage played an important role in the development of the Romanian economy. A stable monetary system facilitated trade and investment and contributed to the modernization of the Romanian economy.