Original:  The kingdom was founded by Koxinga (Zheng Chenggong) after seizing control of Taiwan from the Dutch rule. Zheng hoped to restore the Ming dynastic rule on the Chinese mainland , when the Ming remnants' rump state in the southern China was progressively conquered by the Manchu-led Qing dynasty.
Revised:  The kingdom was founded by Koxinga (Zheng Chenggong) as part of the loyalist movement to restore the Ming dynastic rule on the Chinese mainland , when the Ming remnants' rump state in the southern China was progressively conquered by the Manchu-led Qing dynasty.
Edit intent: clarity