"Goblins have a tribal society, the strongest ruling the rest, allowing fealty to the goblin king."
This quote was by E. Gary Gygax in the 1977 AD&D MONSTER MANUAL. Where this goblin king was nobody got around to it.
In the late 70's and early 80's the default "D&D world" was WORLD OF GREYHAWK. Using the random encounter charts in cluded in the 1983 World of Greyhawk Boxed Set, I have concluded that its most likely the Pomarj. The boxed set encounter charts override the DMG standard charts and here is percentage chances based on the data in the encounter charts. The DMG has "humanoids" including goblins based on terrain. (NOTE: these are only areas that say "goblins" or "humanoids" on the WOG charts otherwise there may be a standard chance of goblins for all areas even ones not included but the likelihood of the goblin king is unlikely.
LOCATION OF GOBLIN KING BASED ON POPULATION OF GOBLINS IN ENCOUNTERS:
POMARJ 6% chance of goblins + 3% G&X goblins and xvarts) [standard DMG 55%]
Compare:
OTHER SPECIFIC GOBLIN ENCOUNTER POPULATIONS:
Bandits 3% Goblin/2% Goblin & Xvarts [standard DMG 40%]
Bone March 3% Goblin/1% Goblin & Xvarts [standard DMG 55%]
Horned Society 2% Goblin/1% Goblin & Xvarts and 2% General Humanoids [standard DMG 50%]
Iuz 2% Goblin [standard DMG 45%]
Rovers 2% Goblin & Wargs and 3% General Humanoids [standard DMG 45%]
Scarlet Brotherhood 3% Goblins [standard DMG 40%]
GENERAL HUMANOID (GOBLIN ON SUBTABLE) ENCOUNTER POPULATIONS:
NW Baklunish States 2% General Humanoids [standard DMG 45%]
Barbarians 2% General Humanoids [standard DMG 40%]
Blackmoor 3% General Humanoids [standard DMG 55%]
Bissel 2% General Humanoids [standard DMG 55%]
Celene 3% General Humanoids [standard DMG 20%]
Dyvers 2% General Humanoids [standard DMG 55%]
Furyondy 4% General Humanoids [standard DMG 10%]
Gran March 5% General Humanoids [standard DMG 35%]
Great Kingdom 7% General Humanoids [standard DMG 30%]
Greyhawk 1% General Humanoids [standard DMG 60%]
Highfolk 2% General Humanoids [standard DMG 55%]
Keoland 5% General Humanoids [standard DMG 45%]
Ket 3% General Humanoids [standard DMG 55%]
Medegia 5% General Humanoids [standard DMG 35%]
Nomads 5% General Humanoids [standard DMG 55%]
Nyrond 3% General Humanoids [standard DMG 50%]
Pale 2% General Humanoids [standard DMG 55%]
Paynims 2% General Humanoids [standard DMG 75%]
Perrenland 4% General Humanoids [standard DMG 50%]
Provinces 3% General Humanoids [standard DMG 45%]
Ratik 6% General Humanoids [standard DMG 55%]
Sea Princes 4% General Humanoids [standard DMG 55%]
Shield Lands 10% General Humanoids [standard DMG 45%]
Spindrift (Lendor) 5% General Humanoids [standard DMG 35%]
Sterich 6%General Humanoids [standard DMG 45%]
Stone Hold 5% General Humanoids [standard DMG 55%]
Sunndi 7% General Humanoids [standard DMG 40%]
Tenh 7% General Humanoids [standard DMG 55%]
Ulek (Prince) 2% General Humanoids [standard DMG 45%]
Ull 5% General Humanoids [standard DMG 60%]
Urnst County 4% General Humanoids [standard DMG 55%]
Urnst Duchy 3% General Humanoids [standard DMG 55%]
Valley of Mage 3% General Humanoids [standard DMG 65%]
Veluna 5% General Humanoids [standard DMG 40%]
Verbobonc 4% General Humanoids [standard DMG 55%]
Wild Coast 7% General Humanoids [standard DMG 60%]
Yeomanry 5% General Humanoids [standard DMG 45%]
GEOGRAPHICAL GOBLIN ENCOUNTER POPULATIONS
(There are no specific goblin encounters in any geographical areas.)
Adri Forest 7% General Humanoids [standard DMG 55%]
Bramblewood Forest 7% General Humanoids [standard DMG 70%]
Celadon Forest 2% General Humanoids [standard DMG 25%]
Dim Forest 6% General Humanoids [standard DMG 65%]
Dreadwood 10% General Humanoids [standard DMG 55%]
Fellreev Forest 8% General Humanoids [standard DMG 60%]
Forlorn Forest 5% General Humanoids [standard DMG 75%]
Gamboge Forest 5% General Humanoids [standard DMG 50%]
Gnarley Forest 5% General Humanoids [standard DMG 50%]
Grandwood Forest 5% General Humanoids [standard DMG 50%]
Hornwood Forest 5% General Humanoids [standard DMG 70%]
Hraak Forest 5% General Humanoids [standard DMG 75%]
Loftwood Forest 10% General Humanoids [standard DMG 70%]
Nutherwood Forest 7% General Humanoids [standard DMG 70%]
Oytwood Forest 5% General Humanoids [standard DMG 70%]
Phostwood Forest 7% General Humanoids [standard DMG 70%]
Rieuwood Forst 5% General Humanoids [standard DMG 35%]
Sable Forest 10% General Humanoids [standard DMG 70%]
Spikey Forest 10% General Humanoids [standard DMG 70%]
Suss Forest 6% General Humanoids [standard DMG 45%]
Tangles Forest 10% General Humanoids [standard DMG 65%]
Timberway Forest 10% General Humanoids [standard DMG 70%]
Udgru Forest 7% General Humanoids [standard DMG 70%]
Eastern Vesve Forest 7% General Humanoids [standard DMG 50%]
Western Vesve Forest 5% General Humanoids [standard DMG 40%]
Welkwood Forest 5% General Humanoids [standard DMG 50%]
Barrier Peak Mountains 11% General Humanoids [standard DMG 50%]
Crystalmist Mountains 11% General Humanoids [standard DMG 50%]
Joten Mountains 11% General Humanoids [standard DMG 50%]
Clatspur Mountains 4% General Humanoids [standard DMG 65%]
Yatil Mountains 4% General Humanoids [standard DMG 65%]
Corusk Mountains 5% General Humanoids [standard DMG 60%]
Griff Mountains 5% General Humanoids [standard DMG 60%]
Raker Mountains 5% General Humanoids [standard DMG 60%]
Hellfurnace Mountains 8% General Humanoids [standard DMG 60%]
Lortmil Mountains 4% General Humanoids [standard DMG 25%]
Sulhaut Mountains 5% General Humanoids [standard DMG 40%]
Ullsprue Mountains 8% General Humanoids [standard DMG 60%]
Abbor-Alz Hills 7% General Humanoids [standard DMG 55%]
Blemu Hills 18% General Humanoids [standard DMG 55%]
Bluff Hills 18% General Humanoids [standard DMG 55%]
Cairn Hills 7% General Humanoids [standard DMG 40%]
Drachensgrab Hills 18% General Humanoids [standard DMG 55%]
Gloriole Hills 5% General Humanoids [standard DMG 20%]
Hestmark Highland Hills 5% General Humanoids [standard DMG 20%]
Howling Hills 18% General Humanoids [standard DMG 55%]
Kron Hills 5% General Humanoids [standard DMG 40%]
Sepia Upland Hills 10% General Humanoids [standard DMG 45%]
Spine Ridge Hills 18% General Humanoids [standard DMG 55%]
Tor Hills 18% General Humanoids [standard DMG 55%]
Tusman Hills 10% General Humanoids [standard DMG 45%]
Yecha Hills 10% General Humanoids [standard DMG 45%]
Dry Steppes 5% General Humanoids [standard DMG 65%]
Rift Canyon 10% General Humanoids [standard DMG 60%]
Vast Swamp 5% General Humanoids [standard DMG 60%]
