Won was introduced in 1902 as the official currency unit replacing yang at 1 won = 5 yang. The bank of Korea was established in 1909 but soon after in 1910 Imperial Japan annexed the Korean Empire. Under Colonial rule, the country was made to use the currency unit "yen" in the place of the Korean Won, which took over the Korean won at par. After the division of Korea, the state of South Korea was established and recognized in 1948, and won was again made the official currency of the new state. "jeon" was made the subunit of the currency that divided it into 100 equal parts. Bank of Joseon issued the currency for independent South Korea for the first time, that too in banknotes only.