Old Sheepskin Scroll can be obtained by exchanging 
Old Sheepskin Scroll fragment 1, 
Old Sheepskin Scroll fragment 2, 
Old Sheepskin Scroll fragment 3, and 
Old Sheepskin Scroll fragment 4 with Old Man Pachkuli (838,929).
The fragments drop from monsters in various locations as bonus loot in popular farming areas. You can find their drop locations in the in-game database.
After obtaining Old Sheepskin Scroll, double-click it to receive one of two maps:
Ancient Pirate Treasure Map — contains coordinates somewhere on the main continent of Ascaron.
Dragon Treasure Map — contains coordinates exclusively on Dragon Island.
The first map is more common, while the second contains more valuable loot.
Each map has a loot table that can be viewed in the in-game database.
Before the first double-click, the map remains unidentified. The first click determines the location and coordinates of the treasure; you can do this from anywhere.
Clicking the map again checks your current location. If you are in Ascaron, it attempts to start Auto Route to the specified coordinates. In any other location, the map only displays the coordinates and area where the treasure is buried.
Once you reach the coordinates shown on the map, double-click it to receive a random item from that map's loot table. The map then disappears.
Restrictions:
- Only one map may be kept in the inventory. Even two maps of different types cannot be stored at the same time.
- OSS can be traded or dropped, but an opened map cannot.
- An opened map cannot be locked or stored in the bank, but it can be deleted.