The original world, tucked away and hidden in the white box, is one of fierce nomadic bands of humans and humanoids that scour the badlands. Why should we think this, when every later edition of the game has portrayed a very different, more civilized setting? A quick look at Volume II gives us our first clues to this barbaric backdrop.
Unlike their later counterparts, original heroes could expect to meet wandering groups of several hundred men and humanoids in the wilderness. Large mobs of humans, in particular, are some of the most common outdoor encounters. This is particularly interesting, given the relatively low numbers of settled communities on the default wilderness map. As others have noted before, the three little brown booklets expected the referee to use Avalon Hill's Outdoor Survival board game for all wilderness adventures, just as much as referee was intended to use Chainmail for combat encounters. Volume III finally gave a scale to this map ("the greatest distance across a hex is about 5 miles", pg 17), meaning each hex represented just over 16 square miles, and the total outdoor map represented 23,740 square miles (or just about the size of West Virginia). It is perhaps surprising that such a massive country has only 9 towns and 26 castles.
Furthermore, we can use the rules for clearing a barony of monsters to determine the average wilderness population of the Outdoor Survival map. In the 1,462 hexes, 601 are clearings, 395 woods, 98 rivers, 36 swamps, 254 mountains and 78 are deserts. By terrain type and encounter odds, this indicates the whole map contains an average of 44 large hordes of men and 41 small parties of heroes. Of the hordes, about 17 are bandits, 12 brigands, 7 nomads, 6 berserkers, 2 dervishes, 2 cavemen, 1 buccaneer and 1 group of river pirates. The heroic parties are equal numbers of fighting-men, clerics and magic-users with an average of 8 individuals per party. All told, this indicates there are 7,588 men roaming the countryside. With only 9 villages on the map, this indicates there are about 843 outcasts per village, which has to be a significant percentage of the total population (if each is a town of 2,500, as S. John Ross suggests, this means one quarter of the human population lives outside city walls).
Granted, Gygax doesn't indicate to us exactly how big each "town" (Volume III, pg 15) on the Outdoor Survival board should be, although the rules for Baronies suggest an estimate of 2,500 is probably not far off. Here, a hero that builds a stronghold is assumed to rule over a base peasantry of around 1,250 villagers in her demesne, some 20 miles distant from the keep. The population density here is about 1 head per square mile, or approximately the same population density as Alaska.
The wandering humanoid population is still significant, although surprisingly lower than the that of men. Compared to the 44 hordes of men, there are only about 6 roaming tribes of orcs (and a similar number of Kobolds, Goblins, Hobgoblins and Gnolls). The relatively lengthy ecological discussion of Orcs in Volume II indicate a possible reason for this. Most of the entry for these humanoids is devoted to their settled life, particularly the defense of their lairs. Half of those found wandering in the wilderness will be escorting wagon trains, which is perhaps evidence of mercantilism. If we assume from this that orcs are at least as settled as their human counterparts, then we can suppose the 990 orcs that wander the Outdoor Survival map are matched by another 3,000 settled orcs (2,000 of which live in caves, 1,000 in villages walled with palisade defenses).
What should we take away from these clues? A world where one quarter of the population is armed and roaming a vast wilderness has tremendous impact on all levels of society. It changes how we should understand the safety of civilization, the economic system, the power of monarchs and how power is conceived generally. With so little stability (one third of the settled populace would have to be constantly mobilized to defend the city walls), rulers would have to rely on shifting alliances with the nomads, and bids for power would likely have rare and dangerous artifacts as their prize, instead of tracts of land or natural resources. Here, the battle between Law and Chaos is sharply realized as a conflict that the forces of order are always on the brink of losing. In this way, the wilderness ecology written into the implied setting of the Original Dungeons & Dragons game tells a striking story of how the early game world might have been imagined. Considering Avalon Hill's Outdoor Survival, combined with the guidelines in Volume II and III, this setting that takes shape is radically different from how those of later official publications were conceived.