Development is a standard that describes the quality of life of the creatures that dwell within a given region. A “region” may be of any size, and based on any criteria the DM may wish. With a sense of practicality, I have chosen to define regional development according to the population density within political borders. This would indicate the typical, or mean level of development for a given region. It would not preclude the presence of a small cell of higher development; such cells, however, would not be considered the norm, and would exist only to serve the DM in actual game play.
The purpose for creating a development measure is to helpfully define small political areas within a gigantic world tapestry, to give them a sense of identity and predictable character. Therefore, it would be meaningless to circumvent a low development region by filling it with high development cells of elite inhabitants. The DM should be encouraged to create adventures that fit the pre-requisite of the region's development, specifically because that limitation helps define one region as recognizably different from another.
Political boundaries and populations, however, are useful only to describe parts of the world that have people (or the D&D equivalent). "People," which includes all monsters with an intelligence of 5 or better on a scale of 18, have not developed every part of the game world. Much of that world is wilderness: uncultivated, inhospitable and uninhabited.
However, rather than consider this wilderness as a single, ill-defined unit, I've chosen to include development levels of 0 to 4 that describe an evolutionary standard of development. The harshest parts of the wilderness would preclude large mammals or other creatures with an animal or semi- intelligence, due to lack of sustenance, water or a reliable biological predation cycle. Regions of less than 5 development are defined by vegetation, topography and hydrography.
Loosely, a development of zero describes a part of the world occupied by insects, molluscs and monsters that lack any intelligence, feeding upon one another in a biome so bleak as to defy even the occasional hunting party a reason for entry.
Conversely, a development of one would include animal-intelligence mammals ~ but the absence of any peoples would indicate that too few mammals would exist to support even sporadic hunting. These would be truly obscure grazing lands, such as those found infrequently in deserts such as the Sahara or Gobi, or in the open ocean. Still, grazing mammals would be the highest form of life.
A development of two would increase the number of grazers, supplying enough predation for family groups of carnivores, such as canines and felines, among other D&D monsters. Hunting parties of intelligent beings may be encountered, but rarely; the size of such regions would be immense and would lack exploitable water supplies for creatures that could not carry their own water supply or travel many hundreds of miles. The lack of exploitable water and resources has already declared such areas (such as savannas in Kenya or Tanzania) accessible but not desirable for settlement (at least, not until the onset of the Industrial Revolution).
A development of three describes the presence of higher intelligence creatures possessing a crude form of communicative language; such as Earth primates. Primitive tool use has not been managed; cooperative forms of attack, or large family groups able to act in concert for attack or defense, make these creatures the dominant creatures in the environment.
A development of four indicates the next stage in semi-intelligence, describing primitive peoples with crude linguistic abilities, strong family bonds and primitive tool use (particularly as weapons), combined with firm social bonds. What we would think of as primitive humans, up to but not including the creation of habitats, aestetics, a comprehension of self or the environment ... so very nearly like a primitive neolithic culture, but not quite.
Further development levels are deserving of their own page of description:
Dev Level 5
Dev Level 6
Dev Level 7
Dev Level 8