What are some grammatical rules or structural rules common to old Dravidian languages?
* I think being prodrop could be one
* Dative construction for involuntary experiences
** Enakku pasikkiradhu (எனக்கு பசிக்கிறது) in Tamil
** Enikku visakunnu (Malayalam)
Roughly to + noun + verb to express experiencing something instead of noun + adjective in English
Also it'd be interesting, are there languages that are Dravidian that do not have such structures?