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So... Chinese territory. Of course China has always had a wealth of words for territory (地，疆土，境内 etc.) going all the way back to the earliest texts, and anyone who says otherwise is talking nonsense. But...
They also had a somewhat different idea of how territory worked than was current in Europe and the Anglo world, and that's actually a pretty interesting topic, so strap in.
In traditional Anglo/Euro visions of politics, power is a protection racket: you give me money and I'll use my army to make sure no one else demands any. In traditional Chinese visions of politics, power is a corporation: you give me money and I'll increase your ROI.
This has implications for how territory is perceived. If your power is based on your ability to protect, then demonstrating that you can maintain hard borders, even around unoccupied land, is vital.
If your power is based upon creating economic surpluses, then you only really care about land insofar as that it's being farmed and generating revenue. Your border is wherever your most distant "investor" is farming. It'll probably be a bit fuzzy and variable, but meh.
(The Great Wall was less a hard border than a base camp, incidentally. They knew it wouldn't stop a really determined invasion force alone, but it would slow it down long enough to mobilise troops while giving them a position from which to keep an eye on things in-between times.)
Going up a level, you can take it even further and say that the border existed less as a line on the map than as a line inside every citizen's head. If his dividends dropped low enough, the state's power over a citizen - whether in the hinterland or the heartland - would vanish.
In that case, either an entrepreneurial new leader will pop up domestically promising more bang for people's bucks, or the state will be overrun by foreign invaders as locals see little incentive to fight on behalf of an authority that is not providing the returns they hoped for.
This explains a lot of the historical Chinese approach to foreign relations. When it came to expanding your power, sending in the army was seen as less effective than making people dependent upon your largesse. Hence the symbolism of the tributary system: https://en.wikipedia.org/wiki/Tributary_system_of_China
(The Wikipedia article actually leaves out the most important part of the process - the fact that after making symbolic donations, foreign envoys would receive *far* larger gifts to take home with them - a ritualised representation of the corporate investor model of power.)
It's still happening today too, with the OBOR initiative and the AIIB. Most of the loans and projects will lose money on paper, but they will also make the recipients increasingly dependent upon Chinese generosity for their livelihoods - a strategic gain for China.
