In a polish game Indians respawned. Then they bet me at discovering Liberalism in 1480AD, which is a little strange, and in the WB I realised that they had discovered rifling in 1480AD! I don't know if this is due to a bug, or wrong modifiers, but Indians should be too backyard at that time, they shouldn't know Gunpowder.
I imagine that Indian subcontinent is too rich, so tech leading Indians is something logical. Moreover, Indian capital, Patna, has two shrines. So inevitably a respawned India in 600AD scenario has a very strong economy and a good research rate, it would be better not to respawn at all. Respawned Tamils would be better, if you want to have a premughal civilisation in India.
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https://www.dropbox.com/s/vk1mpx1omsh9v0r/Sobieski AD-1460 Turn 273.CivBeyondSwordSave