In the normal course of events, when continents move toward each other, at least one coast will be associated with a subduction zone and corresponding volcanic activity. When the Indian subcontinent was moving toward Asia, we would expect such to occur, as confirmed by the answer to Volcanoes in the Alps and Himalayas and the subduction of Tethys Sea
The above also observes that there is no trace of such volcanic activity nowadays; it has been thoroughly buried and erased, which is understandable.
At what point did volcanic activity cease? Would it have been around the time the sea between the two continents disappeared? Or would it have continued for some time after that, resulting in a landlocked but still highly volcanic mountain range?