Milika III was the third planet in the Milika system. This was an inhabited planet.
Early in his career, Jean-Luc Picard led an away team on this planet to save an ambassador. This incident was mentioned by Q as one of the crucial events forming Picard's personality. (TNG: "Tapestry")
Milika III appeared in the starchart Data and Picard were studying in Stellar Cartography in 2371. (Star Trek Generations)
Judging from Q's speech, this probably took place before 2333, when Picard became captain of the USS Stargazer.