I think you can make a pretty compelling case that the Delhi Sultanate and the Mughal empire were cases of politically unified India for several hundred years before that.
Actually upto Arcot in Tamil Nadu. The Nawabate of Arcot was a Mughal governorship that exists even today (in name).
What about the Maurya Empire?
They didn't conquer the Tamil kings, who were merchants probably. And they had spices!
You should probably update Wikipedia then
Not culturally very much. They were probably managed by sub-kings (I forgot the english word). Not a lot changed in South under Mughal rule, compared to north.