Written by MSG Commander
There are a number of areas on the World Map that are not "marked" or otherwise identified, and so the only way to find these areas is by exploring the entire world. Then, by fighting random encounters in a new area, you can look up the enemy you just fought and check their location in the Enemy Guide. This is the only way to find out the name of the "unmarked area" that you're in - except, of course, for using this handy dandy Unmarked Areas map!
Barrel Region (orange)
The Barrel Region is also the location of one of the four Sign Posts around the world.
Drops can include Growth Mushroom, Barrel Ring, Repel Ring, Magic Gummy, Magic Jelly, Mossy Gem, Bronze Gem, Magic Pudding, Magic Matter, Tray Gem, Rusty Gem, Silver Gem, and Gold Gem.
Boulder Region (red)
The Boulder Region is also the location of one of the four Sign Posts around the world.
Drops can include Heal Potion, Boulder Ring, and Encounter Ring (plus whatever the random enemies in this region might drop.)
Gold Dunes A (yellow)
Good place to farm for Gold (and the EXP is alright, too.)
Drops include Lodestone (S), (M), and (L).
Level 200 Area (blue)
Drops in this area can include Heal Matter, Revive Matter, INT+ Arkstone, Magic Matter, Heal Elixir, Brionac, Mighty Salt, VIT Seed, INT Seed, STR Seed, and Steel-Wool Dress.
Level 300 Area (green)
The Level 300 Area is also the location of one of the four Sign Posts around the world.
Drops in this area can include Growth Mushroom, Heal Elixir, STR Seed, Heal Matter, HP Seed, VIT Seed, Revive Pudding, Revive Matter, Dragon Headdress, STR+ Arkstone, MP Seed, INT Seed, and Beef Soup for the Soul.
Level 400 Area (purple)
Drops in this area can include Magic Matter, Alto Heal Matter, Life Seed, Revive Pudding, Revive Matter, Antibacterial Coat, Virus Remedy, SPD Seed, Shining Knuckle, Four-Leaf Clover, INT Seed, Lodestone (L), and STR Seed.
Metal Isle A (light grey)
This island is also the location of one of the four Sign Posts around the world.
Metal Isle B (dark grey)
This is the best place to level up to about 600. After that you can stay here and grind to 999, or you can go to Fairyland.
* The Metal Isles are great for gaining EXP, as long as you're set up to handle metal monsters. For details on how to grind in this area, see the Easy Leveling Guide.
Drops on the Metal Isles include Heal Pudding, Cure Matter, Metal Arkstones, and 30 Arkstones.
The battles here are tough, but if you're around level 600, you can handle them on Normal difficulty (and then slowly raise the difficulty to Hard and Expert, as you get more comfortable here and your level rises some more.)
Drops here include Maid's Brew, Maid's Tincture, Seeds, and the occasional Muramase.