Original: In less than a year, he captured Fort Provintia and besieged Fort Zeelandia; with no external help coming, Frederick Coyett, the Dutch governor negotiated a treaty "Koxinga-Dutch Treaty (/O1662/O)" Appendix 1 to Bullard, Monte R. (unpub.)
Simplified: In less than a year, he took Fort Zeelandia and made an agreement "Koxinga-Dutch with Frederick Coyett, the Dutch governor.