Yeah, I'm obviously complaining primarily because this makes my life harder (I'm trying The White Elephant), but I really got baffled by this.
Hkamti Long and Tamanthi had just been conquered by Ava in a defensive war in which they helped their ally Lan Na against Mong Yang. 1-2 months later, Ming declared with the Force Tributary CB. They then got Ava as a Tributary, made they return cores, and ate two provinces.
...why? This doesn't benefit them. Those provinces are wrong-culture, wrong-religion. Ming's new neighbors (Assam and Kachar) already were Tributaries. Had they let Ava keep at least one province, they'd have >33 development and therefore contribute Monarch Power as tribute. As they are, they have only 31 dev and wouldn't be able to give mana even if they wanted to. Curiously, they did the same with Mong Yang a couple decades ago but apparently returned the provinces to them (I imagine there's a Tributary event for this).
So, like, is this an oversight, or is it WAD? I'd expect the Emperor of China to avoid expanding unless it's land from a rival, or somehow strategic (CoT, Gold, high dev etc). In fact, I'd expect the Force Tributary CB not to allow to take provinces.