Sanatana Can't be limited Geologically or Politically. Though the origin of it is in Indian Subcontinent as it has boomed past all barriers and spread Globally. because the very inception of Sanatana is Cosmical. 

For any Ideology, School of Thought or Way of being it takes the number of Adopters to survive and propagate and it takes Truth for count of Adopters.

Sanatana or Hinduism is the only oldest known, still surviving way of being which has noticed and accepted the Theory of Evolution. 

Scientific Estimates show it was 2.5 million years ago early set of Humans called Homo Hibilis have arrived, and it was only 6000 years since writing started, So the recorded history talks mostly about these 6000 years within which off course we have made a tremendous material progress. but we have lost a great deal of knowledge that has been orally transferred from one generation to another Generation.  Invasions and Colonialism are another two reasons for the irreversible loss of knowledge.  

Despite all the greatness we have lost our Majority to two younger Abrahamic religions. Well all is not lost because the word Sanatana itself means Eternal that which exists forever. We are currently a collection 1.2 billion people on a global scale. If we unite, come together, we can make sure what is existing can be well preserved and passed on to next Generations. 

The Source Language of Sanatana Knowledge is Sanskrit. but for the sake of fesability and far reach we have currently opted for English Language, but all the Significant modules will be in available in Vernacular Languages