When contrasting one part of a region to another an adjective is necessary. This usually takes the form of a compass adjective such as Western Europe versus Eastern Europe. But in some cases those adjectives do not suffice, and a region-specific adjective is necessary; as in the case of Sub-Saharan Africa.
However, I cannot think of an acceptable adjective to differentiate the present-day geographic extent of India to the Indian subcontinent as a whole. The intended use is in the context of talking about British India when Pakistan, Bangladesh, and Myanmar were part of "India".
An example sentence:
The outcome was much the same in Burma as it was in ______ India.
My initial thoughts were "mainland India" or "peninsular India". But I find both to be unsatisfactory and insufficiently self-explanatory.
Suggestions would be greatly appreciated.