S
UGIITakeshi
This article examines the rise and decline of settlements in the late Yayoi and early Kofun periods and the trend of constructing mounded tombs (keyhole tombs) for powerful chiefs in the early Kofun period in the Kumamoto area. This study finds that no prominent early tombs were built in the Kikuchi River Middle Basin, which was prosperous in the late Yayoi period, while a cluster of early tombs for prominent chiefs was formed at the root of the Uto Peninsula, which was relatively worse off in those days. Although the geographical features, such as rivers and plains, imply that farmers, especially rice producers, in the Kikuchi River Middle Basin had much higher productivity than those at the root of the Uto Peninsula, this high productivity was not directly related to the creation of mounded tombs or maintenance of settlements in the early Kofun period. In other words, the territories of large settlements serving as district centers in the late Yayoi period did not coincide with the areas where prominent chiefs’ tombs were constructed in the early Kofun period, at least in the Kumamoto area.
The root of the Uto Peninsula is considered as the southern border of the Yayoi culture, whose elements, such as burial jars and bronze weapons, have characterized the northern Kyu¯shu¯ region.
The central government, located in the Kinai region, introduced various hierarchical elements into the tumulus system and used the order built on them to establish its position as the mainstay of the state.
The geographical range of influence of the government, presumed from the distribution of keyhole tombs, is considered to have coincided with the areas where rice production was accepted as a means of livelihood in the Yayoi period. If this is the case, the root of the Uto Peninsula on the southern border of the Yayoi culture, which was dominant in the northern Kyu¯shu¯ region, seems to have been regarded as the forefront of the inside world from the perspective of the central government. In other words, it is presumed that some of the first large keyhole tombs were constructed at the root of the Uto Peninsula because the central government placed a particularly high value on the area as a symbol of solidarity of the inside world (vs. the outer world).
Thus, some keyhole tombs were constructed outside the conventional economic sphere. This fact clearly indicates that tumuli were of considerable political significance.
Key words: Late Yayoi period, early Kofun period, settlement, chief-tomb cluster, Kumamoto area
0 20km
（1/40 万）
菊池川
坪井川 白川
緑川 浜戸川
潤川
砂川 氷川
坪井川
井芹川
友田川
行末川 山田川 繁根木川
木葉川
江田川 合志川 迫間川
菊池川
河原川
小野川 塩浸川
豊田川
矢護川 合志川
河内川
堀川
白川 黒川
木山川 秋津川
矢形川
御船川
大野川
郡浦川
上生川
下岩野川
球磨川 水無川
加勢川 川辺川
有 明 海八 代 海
立野火口瀬
玉名湾
鹿
盆 地
金峰山
熊 本
平 野
宇 土半 島
阿 蘇 谷
南郷 谷 阿 蘇 山
江津湖 岡花
山
神園山 立田山
熊本湾
熊本城
大鼠蔵
天
草
図 1 熊本県地域の地理
1-3 5
3334
37 35 36
38 39
40
41 42
43
44 45 32
31 29 30
28 26･27 25
24
23 22 16
17 18 19-21 9 1012
11 136-8 15 14
47 46 48 49
53 54
55
56 57
58
59 60
61
62
63 64
65 66
67
69 70
7172
7374 75 7677 78
79 80 81 82 83
84
85 86 87
88 89
90 91
92 93 94-96
97 98-99
100 101
102
103 104
105 106
108 107 109 110
111
113 114
115
116 117
118 119
120 121
122 123
124 125 126
127 128 129
130 132 131 133 134 135 136 137 138
139 141
142-144 145･146
147 148 4
50 51 52
112
140
68
長胴以前の甕も出土した遺跡
球形胴の甕のみ出土の遺跡 弥生後期の溝 （環濠 ) 検出遺跡
※番号は表 2 の遺跡番号に対応 0
20km
（1/40 万）
菊池川
白川
加勢川 緑川
浜戸川
砂川 氷川
球磨川
坪井川井芹川
木葉川
菊池川
白川 黒川 合志川
山田川 繁根木川
江田川
上内田川
迫間川
矢護川 塩浸川
上生川 小野川
下岩野川
秋津川 木山川
矢形川
御船川
潤川
大野川
行末川
友田川
岩野川
江津 湖
有 明 海八 代 海
玉名湾
菊 鹿
盆 地
金峰山
熊 本
平 野
宇 土 半 島
阿 蘇 谷
南郷 谷
阿 蘇 山
熊本湾
天
草
図 2 熊本県地域における弥生時代後期から古墳時代前期にかけての主要集落遺跡の分布