Briefly, its genesis was in the Commonwealth Bank of Australia, which was established by legislation in 1911. In this early incarnation, the Bank only had the ordinary functions of a commercial and savings bank. But over the succeeding years it gradually took on a number of activities that are typical of central banks.
It was given control over note issue in the 1920s and then progressively acquired exchange control powers and controls over the banking system. The Bank’s powers in relation to the administration of monetary and banking policy and exchange control were formalised in legislation in 1945. Then in 1959, the Commonwealth Bank was effectively split into two.