[While writing the recent entry on Servitude I noticed I had this piece in my notebooks. The topic here is system-level consequences of changes in micro-structure, not the evolution of the inner meaning of the master-slave relationship, but there is a connection to a topic that came up indirectly in the essay on servitude: the emergence of elite ideologies as means of forming alliances between scattered local elites.]
During the prehistory of Eurasia, outside of the floodplains, settlement centered (literally) on little proto-cities. As one city grew, the imperium of the city stayed strongest in the forum itself and grew weaker in the hinterlands. The growing city eventually came into conflict with neighboring cities; the loser degenerated to a town or, sometimes, to a ruin. The victor slowly became a metropolis.
The result was an extremely uneven utilization of land. Conquered provinces were simply drained of resources, and provincial capitals reduced to points of transit for tribute. The metropolis saw the most development, but this was distorted by the courtly character of the imperial system; buying off popular support, military support, and elite support obviously trumped “development” in an economic sense.
The ecology of proto-cities could not expand without destroying the proto-cities themselves. But without the proto-cities, industry could not acquire any sort of reasonable efficiency; there was no synergy between the site of production and the site of consumption in the classical countryside, since the market was the metropolis; but there could be no level of productivity justifying such a severe and transport-intensive division of labor until there was development in the countryside.
Therefore latifundia and manoria were the first step in moving population back into self-sufficient rural communities which would create demand for goods on a locality-to-locality basis. The dissolution of the large imperial units of administration into the smaller feudal units, with their autarchic quality, continued the same process. The feudal manor allowed more intensive use of the resources of each region, but also allowed the medieval communes to grow up in the pores of the duchies. This allowed the growth of a system of “international” (previously, it would have been interprovincial) trade in which not just the products extracted were traded, but also worked up materials like cloth and silk.