Why is Taiwan called by island bastion of nationalist china?

Taiwan is referred to as the island bastion of nationalist China due to its historical and political context. After the Chinese civil war in the 1940s, the nationalist government led by Chiang Kai-shek retreated to Taiwan, establishing the Republic of China (Taiwan).

Since then, Taiwan has been recognized by some countries as the legitimate representative of China, while the People's Republic of China (PRC) on the mainland claims sovereignty over Taiwan and considers it a breakaway province.

As a result, Taiwan has become a "bastion" or a stronghold of nationalist China, representing the continuation of the pre-1949 Chinese government and its political ideology.