Chiang Kai Shek played an instrumental role in the founding of Taiwan, but Sun Yat-sen played an instrumental role in the founding of both The People’s Republic of China AND the Republic of China. In the early 20th century, he led a revolution against the monarchy in China and founded a republic. He’s considered the Father of the Nation for BOTH the People’s Republic of China and the Republic of China.
By the mid 19th century, the power of the Qing Dynasty was waning. Once a proud empire, the Qing Dynasty suffered a series of humiliations through various wars against European powers and the Empire of Japan (known historically as the century of humiliation). The unequal treaties that the empire had no choice but to sign caused China to cede control of various ports to these foreign powers (hence the reason why Hong Kong became part of the British Empire).
As the Qing Empire continued to be bullied, resentment grew among the people. Out of this resentment, eventually resulted in revolution. Sun Yat-sen tried on many separate occasions to overthrow the empire. Even after a string of failures and exile, he persisted, and eventually achieved his goal of overthrowing the empire and founding a republic.
The republic however was short lived. Plagued by power struggles, the republic fell apart. Sun Yat-sen passed away before he could see his successor, Chiang Kai-shek reunify the nation. But even that was short lived, once Japan began invading China and then the resumption of the Chinese Civil War almost immediately after.
See more pictures of Taipei here