The sovereignty of Japan over Taiwan under the 1895 Treaty of Shimonoseki continued until its defeat at the end of World War II; but sovereignty over Taiwan after the war is more difficult to resolve. The 1943 Cairo Declaration by the United Kingdom, China, and the United States seemed to express an intention to return the islands to the ROC, at that time still the only Chinese government. The 1945 Potsdam Proclamation evinced the same intention. Since neither was a treaty or other legally binding instrument per se, these documents did not directly transfer sovereignty over the islands. The multilateral Peace Treaty of September 1951 did have the legal effect of formally surrendering Japanese sovereignty over Taiwan, the Pescadores, and arguably the Diaoyu Islands, but China was not a party to the Treaty, through either the ROC or the PRC. Moreover, the Treaty did not specifically identify the entity that was to inherit Taiwan. That question was not clarified by the bi-lateral Peace Treaty of 1952
between Japan and the ROC, which simply recognized Japan's renunciation in the multilateral Peace Treaty of 1951.
Thus, none of the post-World War II peace treaties explicitly ceded sovereignty over the covered territories to any specific state or government. Rather, they formally nullified the sovereignty of Japan that was derived from the 1895 Treaty of Shimonoseki.