The above is absolutely true. It is also tangential to the OP and not what I was discussing in the slightest.
The OP concerns, unless I am mistaken (in which case
@Koprulu Mustafa Pasha, please correct me), the possibility of Afghanistan acting as an Indian analogue to Manchuria in that the locals of that region manage to conquer a vast swath of territory directly adjacent to their homeland and, over time, are assimilated into the populace that they had conquered to the point that, at a certain point, their homeland becomes an integral part of the conquered peoples' nation and their own people lose a distinct identity and become another subset of the natives of the land their ancestors conquered.
I posited that it would not be an apt comparison and unlikely to happen bar major changes in geography, politics, etc. as Afghanistan lacks the qualities that helped attract Han settlement during the Qing dynasty, which was part of the process that led to the loss of a separate Manchu identity and culture and the integration of Manchuria into China proper. There is little that would push tens of millions of Indians to settle Afghanistan the way the Han flooded into Manchuria during the Chuang Guandong, which led to the current clear Han majority in Manchuria in the present day. Afghanistan lacks the fertile farmlands that would attract poor, landless peasants, the safety created by gunpowder and Qing diplomacy+force that enabled the settlement of the region (mountains making it much harder to root out dissenting locals and Afghanistan has historically been difficult to unify, at least in part due to its rough terrain), and the ease of actually settling the area (Afghanistan's landscape is difficult to traverse, which limits both the number of potential settlers and the range of lands that they can easily reach) of Manchuria.
Nowhere did I mention that India would not have any incentive to conquer or retain the region, simply that it would not easily become yet another Indian province the way Gujarat or Rajastan are and its people would not simply slip into the passage of time and go extinct by their own success.
Tibet is neither fertile nor does it have a Han majority. As of 2011, a bit over 90% of Tibet's 3 million people are Tibetan and under 10% are Han Chinese. Tibet is of great strategic importance to China, yes, but that does not incur mass migration and massive demographic shifts, nor does it lead to the locals assimilating into Chinese culture. Xinjiang would be a better counterpoint but the Uyghur are resisting assimilation and the Han are not an overwhelming majority as they are in the Dongbei, nor did the Uyghur conquer China and thus create their own circumstance, which does not fulfil the OP.
As for Aksai Chin, I can't easily find demographic information on that region but it doesn't fulfil the 'conquered the region it got colonised by' condition anyways.
I did not say these regions were not valuable to the nations they border/are in; rather, I said they wouldn't attract much settlement because they weren't attractive for settlement because of poor land fertility and rough terrain, which has rather proven true when compared with Manchuria, which saw a flood of poor Han farmers when settlement was allowed, and that settlement was a key component in the dissolution of the Manchu identity and homeland into the greater Han Chinese identity and homeland.