There are 2 unique codex entries in the Locations section on Makeb. They are both faction specific.
Stronghold One is obtained from speaking with Katha Nar during "A World Aflame" mission.
Codex type: Locations | Faction: Imperial | Class: All
Associated Achievement: None
Talaos City is obtained near a proximity map trigger.
Codex type: Locations | Faction: Republic | Class: All
Associated Achievement: None