In December 1948, the government of North China announced the establishment of the People's Bank of China and introduced the first series of renminbi to replace various currencies in regions controlled by the Communists. By late 1951, the renminbi became the sole legal tender in China, except in Taiwan and Tibet, replacing the old yuan at a rate of 1 to 10,000, putting an end to hyperinflation and contributing to the economic unification of the country. In March 1955, a second series of renminbi was introduced to address flaws in the first series, with a conversion rate of 10,000 yuan from the first generation equaling 1 yuan of the second generation, marking an improvement in quality and security against counterfeiting. This evolution of the renminbi strengthened the Communist regime's economic control in China.