ARTICLE 1. The territory of the Republic of China consists of the various provinces and Mongolia and Tibet.
Note that this refers to the provinces as they were considered in 1931, which means it includes all the concessions by PRC to Russia, Vietnam etc.
We can reach the same conclusion by understanding that the ROC holds itself as the sole inheritor of Qing, thereby all its lands. These lands are what they use for the outline of China, such as in the emblem of their marine corps.
I will say in parting that this doesn’t mean the people of Taiwan island necessarily consider their government to be the rightful governors of PRC lands, let alone the rest of these claims. They have no intention or desire to invade Mongolia. Indeed, they may not have in 1947, and therefore didn’t make any mentions of Mongolia or areas ceded by CPC. Regardless, successive governments have made no attempts to clarify this with new legislation.
There’s no clear territorial definition of what constitutes the area of the ROC in their constitution. It mostly refers to a mainland, defined as the areas controlled by Chinese Communists.
Provisional Constitution Of The Republic Of China (1931) has one though, which is what’s alluded to in the constitution:
Note that this refers to the provinces as they were considered in 1931, which means it includes all the concessions by PRC to Russia, Vietnam etc.
We can reach the same conclusion by understanding that the ROC holds itself as the sole inheritor of Qing, thereby all its lands. These lands are what they use for the outline of China, such as in the emblem of their marine corps.
I will say in parting that this doesn’t mean the people of Taiwan island necessarily consider their government to be the rightful governors of PRC lands, let alone the rest of these claims. They have no intention or desire to invade Mongolia. Indeed, they may not have in 1947, and therefore didn’t make any mentions of Mongolia or areas ceded by CPC. Regardless, successive governments have made no attempts to clarify this with new legislation.