A rare treasure map is an item in Evony TKR (The King's Return). It can be found after killing certain monsters or bosses, with some of them listed below.
The description of Rare Treasure Map in Evony TKR says:
Use it to locate a Lv3 Relic to search for Treasures.
Rare Treasure Map is known to drop from a number of bosses or monsters upon killing, including Manticore and Yasha.
Note: This list may be incomplete.