Personally I would be happy with at least these three civ from the region:
- MAGADHI civ, the northeastern classical Indo-Aryan empires based on Pataliputra like Nanda, Maurya and Pala. Covering the apogee of buddhism in what is now not just India but also Bangladesh.
- TAMIL civ, the southern medieval Dravidian empires like Chera, Chola and Pandya. Mostly devoted hinduists with a focus on naval trade expanded beyond India and Sri Lanka to SEA.
- GURKANI civ, the northwestern modern Turkic-Iranian empires with core on the Indus River Valley, representing the Mughal (also indirectly the similar Tughlaq and Lodi dynasties). The period of the expansion of islamic dynasties from Central Asia, Iran and Afghanistan over the subcontinent, the reason why most of the river that gives the name to India is currently in a different country, Pakistan.