When did the Kuomintang turn against Bias Bay pirates?

What was the relationship between the Bias Bay pirate groups and the Kuomintang?

Once Chiang Kai-shek gained firmer control and sought European arms, he had strong reasons to suppress them and demonstrate stable government.

The relationship changed as Chiang Kai-shek consolidated firmer control. A government seeking weapons from Europe benefited from appearing orderly and capable. Suppressing pirates therefore supported both security and diplomatic credibility. The answer links counter-piracy to state formation rather than presenting local gangs as isolated criminals. It also explains why cooperation could improve when a Chinese central authority saw institutional advantage in acting.