On March 17, China formally resumed diplomatic relations with the tiny West African nation of Gambia after 21 years. The two nations had cut ties in 1995 when Gambia became one of a handful of African countries to formally recognize Beijing’s rival, Taiwan. The re-establishment of ties between a rising great power and one of Africa’s smallest nations is in and of itself not noteworthy. However, Gambia and a host of other marginal international players have been part of a decadeslong contest between Beijing and Taipei for international recognition as the rightful ruler of Chinese territory. With the loss of Gambia, only 22 nations now acknowledge Taiwan’s government as the legitimate representative of the entirety of China....