XII & Revenant Wings take place thousands of years in the past.

Tactics Advanced and TA2 are meta-fiction games where someone from the real world entered imaginary fanfiction of those games.

Tactics takes place to the West of Rozarria and the original Ivalice, thousands of years after some calamity killed off a lot of the races in XII.

Vagrant Story is a few decades or centuries after, somewhere in the remains of the Arcadian empire.

The Ogre Battle games likely share the same universe, as they have Zodiac Stones and divine-chosen Dynast Kings. I suspect they take place earlier, since Denam rises to power from a lowly nobody but in Tactics, kings share his name (Denamunda dies just before the game). My educated guess is they take place across the sea somewhere to the northwest. The Ivalice games were likely originally conceived as Episodes in the Ogre Battle Saga (OB:MotBQ is Episode V, Tactics Ogre is Episode VII).