Fig 2 Examination of visibility
GEOGRAPHICAL DISTRIBUTION OF SITES
Our analysis on geographical distribution of nucleus village sites and hill-fort sites starts with definition of the network described previously. An example of the region for our experiment is a 40 km×40km square region including Yodo River running over both Kyoto and Osaka Prefectures. There are 24 nucleus village sites and 14 hill-fort sites in this region respectively.
Distribution of sites
The village network of nucleus village sites has been defined by k= 0.4 in (2). This value is set by trial-and-error to obtain a network similar to the result obtained by archaeologists [1,2].
Fig 3 Distribution of sites on the terrain map
In order to obtain the beacon telecommunication network between hill-fort sites, we set the two parameters as h=12.3km and r= 30.2m, respectively. From our simulation, we could recognize that three hill-fort sites were very distant from nucleus villages. In contrast, since the other 11 hill-fort sites were fairly close to nucleus village sites, they were regarded as being closely connected to nucleus villages.
Neighbouring sites
We next estimated which nucleus village site relates to which hill-fort sites by considering distances between the sites which are connected in the village network as given above. Each village would have an extent of its territory. Simply, we assumed that the boundary between two sites was the middle of both centers. Then, we also assumed that every hill-fort site related to its nucleus village site should be within a circle area, around the center, within a radius of half of the distance from the neighbouring village. The mean distance between nucleus village sites in the network was computed as 5.48km. So we drew a circle 55km in diameter for each nucleus village on the map (See Fig.3). The beacon telecommunication network is also drawn to give references for our estimations. We could find that two types of hill-fort sites exist in the map; one was near the circles and another was away from the circles. The first type included 9 sites and the second includes five sites. Hereinafter, we propose to take only the first type of nine sites for our consideration.
