"Northern Alliance" was the name Lia had given to the alliance with the two powerhouse sects, Flower Dark Sect and Heavenly Demon Sect. And with it, Lia used its name to impose influence on the small clans she seized.
At first, Lia wasn't thinking of seizing the small clans, but only the dark sects, since they were more of a pain in the head. But as she realized how obedient they were, an idea popped into her head.
Lia seized the small clan that had offended her. It might be unreasonable, but this is how she is. She doesn't care about anyone's perspective; she wants to spread their influence and have control over them before Yuna finishes her two-year seclusion cultivation.
Lia would go to small clans and push fear into their systems. But of course, no matter how cruel she was in a slight manner, she promised to not push tyranny.