A conventional view of state formation is that the role of warfare is to enable emergent states to compete for additional territory and resources when population pressure becomes intense. In other words, warfare primarily occurs when groups of people are forced to compete for scarce resources and this is a part of the formation of states.
However, evidence presented from the history of Korea suggests that this is not always the case. We know that the history of Southeast Asia provides an example of a region of peoples who used warfare as a means of obtaining resources, especially labour, so as to promote the strength of existing communities. In other words, people were not viewed as dependent mouths to feed but as providers and creators of wealth, through taxation and corvée labour. Evidence from early Korea suggests that this challenger to the conventional view is also applicable there.
This evidence* suggests that rather than population pressure leading to warfare, instances of warfare are quite closely (positively) correlated with incidences of environmental stress (e.g. drought, locusts, snow etc.). That is, the inference is that when environmental stress puts pressure on the existing level of resources, states will resort to warfare in order to capture (or recapture) the resources necessary to bring their standard of living back to the previous level.
However, the seventh century is treated as an outlier in this analysis since the incidences of warfare were much greater in this century, resulting from social and political factors - i.e. unification of the Korean peninsula. In other words, political factors can cause variations to the underlying pattern.
An additional point concerns the population of ancient Korea, which is estimated at being around 950,000 for the early centuries CE. Annual growth of the population is estimated at just below 0.4% and average household size 5. This is consistent with evidence from elsewhere of an annual population growth rate of 0.3-0.7%, interspersed with periods of stagnation or even decline. The population doubles every 250 years or thereabouts.
* Kang, Bong W., “A Reconsideration of Population Pressure and Warfare: A Protohistoric Korean Case,” Current Anthropology, Vol.41, No.5 (December 2000), pp.873-82.
