Taiwan does not have a UN membership. Most states do not
recognize Taiwan as a sovereign country, including Singapore.
The Republic of China lasted from 1912 - 1949 on the mainland. When
the defeated KMT forces retreated to Taiwan, Taipei became the
UN-recognized capital of China from 1949 - 1971.
The People's Republic does not recognize this and considers the
Republic of China extinct in 1949.
After Nixon visited China, both USA and China agreed to work
together to face the impending threat from an aggressive USSR. In
1971, the UN seat was switched to PRC and the people of Taiwan lost
their UN representation.
Beijing replaced Taipei as the new capital of China.
Like it or not, that is the way international politics works.
