Monograph No. 62



English Table of Contents and Summary


Nara National Cultural Properties Research Institute (Nabunken)



Report of Archaeological Investigations into the Zuto Stupa, Nara Japan


Table of Contents

Chapter I: Introduction   1

A. What is Zuto?   1

B. Background of the investigations   2

C. Preparation of the site report   3

D. Abbreviations   4


Chapter II: Historical Background of Zuto   5

A. “Head Mound” of Gembo   5

B. Hypothesis of an earthen stupa erected by Priest Jicchu in 767  5

C. Structure of Zuto: Hypothetical reconstruction   6

D. Meaning of stone images of Buddha   7

E. Historical background of the erection of Zuto   7

F. Initiating archaeological investigations   8


Chapter III: Archaeological Investigations   10

1. Over view of archaeological investigations   10

A. 114th excavation   10

B. 181st excavation  10

C. 119th excavation  12

D. 232nd excavation  12

E. 237th excavation  14

F. 247th excavation  14

G. 257th excavation  14

H. 264th excavation  15

I. 277th excavation  15

J. 282-15th excavation  15

2. Excavation log  16

A. 114th excavation  16

B. 181st excavation  16

C. 119th excavation  18

D. 232nd excavation  19

E. 237th excavation  20

F. 247th excavation  21

G. 257th excavation  22

H. 264th excavation  22

I. 277th excavation   23

J. 282-15th excavation   25

3. Plan and over view of the restoration of Zuto   26


Chapter IV: Archaeological Features   28

1. Formation of the archaeological site   28

A. Topography prior to the erection of Zuto; process of the erection   28

B. Stratigraphy of the site; topography prior to the archaeological excavations   30

2. Zuto 32

A. Zuto in the lower stratum (Phase A)   32

B. Zuto in the upper stratum (Phase B)   43

C. Zuto after the Heian Period (794-1185)   60

3. Other archaeological features   64

4. Kofun Period burial mound in the lower stratum of the Phase A Zuto   66


Chapter V: Artifacts   68

1. Rooftiles   68

A. Round eaves tiles   68

B. Flat eaves tiles   71

C. Round and flat rooftiles   73

D. Roof ridge tiles and gap-fill tiles   74

2. Stone images of Buddha   76

A. Stone images of Buddha on the north face of Zuto   76

B. Images on the east face   78

C. Images on the south face   79

D. Images on the west face   81

E. Central motifs of the stone images   82

3. Artifacts discovered in the pit resulting from the removal of the central pillar on the top of Zuto   83

A. Bronze coins tied by a cord   83

B. Amber beads   85

C. Ash, charcoal, and wooden boards   85

D. Bronze coins discovered in a pit dug by looters   86

E. Scientific analyses of the bronze coins and amber beads   87

4. Pottery   89

A. Pottery excavated in the mound constituting Zuto   89

B. Pottery used for rituals in front of stone images of Buddha   90

C. Pottery discovered on the mound surface and the vicinity   91

5. Miniature stone pagodas   93

A. Stone pagodas with hexagonal roof   93

B. Other types of stone pagodas   93

6. Stone and metal artifacts   96

A. Stone artifacts   96

B. Metal artifacts   96

C. Miscellaneous   97

7. Artifacts related to the Kofun Period burial mound in the lower stratum of the Phase A Zuto   98

A. Weapons   98

B. Horse trappings   99

C. Tools   100

D. Accessories   100

E. Pottery   101

F. Scientific analysis of glass beads   103


Chapter VI: Discussion   104

1. Selection of the location for the erection of Zuto   104

A. Spatial relationship with the Shijo (Fourth Major) Street of the Nara Capital   104

B. Spatial relationship with the main axis of the Todai-ji temple complex  106

C. Meaning of the location of Zuto  106

2. Temporal change in the physical structures of Zuto and their calendrical dates   107

A. Construction of the Phase A Zuto   107

B. Construction of the Phase B Zuto   108

C. Temporal change in the Phase B Zuto   109

3. Hypothetical reconstruction of the structure of Zuto   111

A. Phase A Zuto   111

B. Phase B Zuto   112

C. Structure of the roof   122

D. Piling up the earth and stones to erect the mound   124

4. Rooftiles   126

A. Eaves tiles in the Phase A and Phase B   126

B. Temporal change in the Todai-ji type eaves tiles and their distribution   126

C. Calendrical dates and distribution of rooftiles other than the Todai-ji type   132

D. Roof of Zuto   134

5. Zuto as mentioned in historic sources   141

A. Various issues concerning the date of the initial construction of Zuto   141

B. Zuto after the construction   147

C. Chronology related to Zuto   152

6. Religious and ideological background to the construction of Zuto   155

A. Ideology behind the erection of the colossal Buddha at Todai-ji   155

B. Ideological and religious background of planning the Phase B Zuto   156

C. Ideology behind the construction of the Phase B Zuto   158

D. Ideology behind the construction of the Phase A Zuto   159

7. Genealogy of Zuto as a stupa   164

A. Similar stupas in Japan   164

B. Hypothesis of the southern origins of the Zuto-type stupa   165

C. Hypothesis of the Korean origins of the Zuto-type stupa   166

D. Hypothesis of the Chinese origins of the Zuto-type stupa   169

8. Reconstruction of tuff pagoda with hexagonal roofs   174

A. Hexagonal pagodas in the Nara and Heian Periods   174

B. Reconstruction of the stone pagoda at To- no-Mori, Nara   177

C. Hypothetical reconstruction of the stone pagoda on the top of Zuto   180

9. Sourcing the stones used for the Zuto construction   182

10. Kofun Period burial mound in the lower stratum of Zuto   184


Chapter VII: Summary   191

A. Structure of Zuto and its temporal change   191

B. Historical background to the construction of Zuto; genealogy of the Zuto-type stupa   192


Supplementary tables   193

English summary   199





This book is a report of archaeological investigations conducted at the site of Zuto, 頭塔 a Nara Period (710-794) earthen stupa. It is located in Nara City, approximately one kilometer south of the Todai-ji  東大寺 Buddhist temple. It is an earthen mound, with the surface paved with stone slabs and roofed with tiles. Ten times of archaeological excavations were conducted by staff of the Nara National Cultural Properties Research Institute from 1978 to 1998, prior to restoring the stupa to its original condition. While previous research into historic sources suggests that Zuto was constructed by Priest Jicchu  実忠(?-?) of Todai-ji in 767, the excavations revealed two stratigraphically over lapping features of stupas, which suggests that the construction of Zuto took place twice. It has also become clear that a Kofun Period burial mound was destroyed in the process of the construction of Zuto.


A. Overview

 Zuto consisted of the top “stupa" portion and the foundation platform. It was quadrangular in morphology. The stupa in the upper stratum (here after Phase B) had a seven-story structure; i.e. it had seven terraces that were paved with stones and seven stone walls. A total of eleven stone images of Buddha were placed on each directional face of the stupa, forty-four all together for the four directions. On the first (lowest) terrace were five stone images of Buddha in each direction, three on the third terrace, two on the fifth terrace, and one on the highest, seventh terrace. The stupa in the lower stratum (here after Phase A) was a three-story structure. Each story had a stone wall, but it remains uncertain whet her each terrace was paved with stones.


B. Structure of Zuto and its temporal change

 Phase A Zuto: The Phase A Zuto was badly disturbed during the construction of the Phase B Zuto, but may be reconstructed to a three-story stupa. We speculate that the construction of this Zuto was once completed.


 The Phase A Zuto had serious structural deficiency. For example, both the foundation platform and stupa itself were not square in plane. Rather, they were trapezoidal, with the north side wider than the south side. Each side of the stupa at its base was not straight. The top of the foundation platform was not level and horizontal, but inclined or tilted. The orientation of the platform and that of the stupa did not match, either. Therefore, the measurements of the various portions of this phase of Zuto varied from part to part. The length of a side of the foundation platform was 31.8 to 33.0 meters, a side of the first story of the stupa from 20.2 to 21.75, the second story from 13.2 to 14.3, and the height of the foundation platform from 1.0 to 1.6 meters. The original plan was to situate the stone wall of the second story and that of the third story upon the two hypothetical lines dividing the length between the center of the stupa and the stone wall of the first terrace into three equal segments. The height of the first story was 3.45 meters. The height of the stone wall of the first story was approximately 2.35 meters. We speculate that the terrace of the first story was adopted with a roof at a gradient of 30%, with rooftiles. A large niche where an image of Buddha must have been placed was discovered at the center of the east face. No other actual images of Buddha have been discovered for the Phase A Zuto.


 Phase B Zuto: The foundation platform for the Phase A Zuto remained to be used. The Phase A stupa portion was, however, pretty much destroyed in the process of the construction of the Phase B Zuto. The Phase B stupa portion was considerably expanded. The possible reasons for this re-construction were: 1) to correct structural deficiencies of the Phase A Zuto; to re-model the stupa portion into a seven-story structure from a three-story one, thereby lowering the height of the stone wall of each story; and 3) to increase the number of Buddha images that were to be placed in each story. Still, the structural deficiencies were not fully corrected, and the following problems remained. The plan of the stupa was rectangular with four different side length, the stone walls of the same story were not parallel, and the foundation platform and the pavement of each story was tilted in the direction of the stone wall.


 The length of each side of the stupa portion was between 24.2 and 24.8 meters, and the height of Zuto was approximately eight meters. The original plan for the entire stupa was: the stone walls for the third, fifth, and seventh stories should be placed on the hypothetical lines that divide the length between the stone wall on the first story and the central axis of the stupa into four equal segments; the stone walls for the second, fourth, and sixth stories should be placed on the hypothetical lines that divide the space between the stone walls of the lower story and upper story into 2:3. The width of the stone pavement and degrees of gradient clearly correlated to each other. The stone pavements on the odd number of stories (second, fourth, and sixth) were wide, and gradient was gradual, between five and ten percent. On the other hand, the pavements on the odd numbers of stories (first, third, and fifth) were narrow, and gradient was steep, between 25 and 30%. This observation suggests to us that rooftiles were only adopted to cover stories of to the odd numbers. On the summit of the stupa was, we presume, wooden one-story stupa roofed with tiles. Under ground of the summit was a base stone, on which the central pillar of the presumed wooden structure stood. On each story of the Phase B Zuto were several stone Buddha images. We presume that five on each face of the first story, three on each face of the third story, two on each face of the fifth story, and one on each face of the seventh story, forty-four in total.


 As to the dates of the construction of the Phase A and Phase B Zuto, several clues are at our disposal. First, our excavations revealed that a Kofun Period tumulus was destroyed during the construction of the Phase A Zuto. In the “Zo Nan-ji Sho Ge” (「 造南寺所解」 Notes on the Construction of Buddhist Temples in Nara, a document kept in the Shosoin 正倉院 Treasury at Todai-ji) was an article that described the destruction of a Kofun Period tumulus in 760 A.D. If this description was indeed for the construction of the Phase A Zuto, it is then possible to suspect that the construction took place in 760. Re-modeling of this Zuto in to the Phase B one probably started around 765. The project completed in 767, as clearly recorded in the Todai-ji Yoroku (『東大寺要録』 Major Records of the Todai-ji Buddhist Temple) and the Todai-ji Betto Shidai (『東大寺別当次第』 Order of the Todai-ji Betto).


 Zuto after the 780’s: At some point in the 780’s, a lightening hit Zuto, and the wooden structure on the summit burned down and was lost. Therefore, the central pillar for the structure was pulled out. Then, tied groups of coins and amber beads were offered to the pit resulting from pulling out the central pillar, rituals were conducted on the summit, and everything was buried in the pit. In the late 790’s or the beginning of the ninth century, coins were buried again, and a land-breaking ritual was conducted on the summit, prior to the erection of a thirteen-story, hexagonal tuff pagoda on the summit. After that, roofs with tiles and stone walls of some stories of this Zuto began to collapse, and stone images of Buddha began to expose themselves. In the Shichidaiji Junrei Shiki (『七大寺巡礼私記』 Personal Notes of Pilgrimage to the Seven Great Temples in Nara) dated to the late twelfth century, Zuto was recorded as a “thirteen-story big tomb,” and probably this record describes such a condition of Zuto at that time.


 In the late eleventh century, memorial services were conducted for the stone images of Buddha by placing earthenware dishes used as lamps in front of them. This event might be related to the Bodai-in 菩提院 at the Kofuku-ji 興福寺 Buddhist temple, which attempted to incorporate Zuto into the Bodai-ji organization after the eleventh century.


 After the fourteenth century, the eastern face of the foundation platform was modified. During the Tokugawa Period (1600-1868), the ownership of Zuto was transferred from the Kensho-in  賢聖院 o f Kofuku-ji to the Jotoku-ji 常徳寺 temple of the Nichiren 日蓮 sect. Zuto became a subsidiary temple of Jotoku-ji. It was also around this time that the southeastern corner and southwestern corner were partially destroyed. Since the beginning of the Meiji Period (in the 1870’s), Zuto has been a national property.


C. Historical background of the erection of Zuto; origins of Zuto


 Ideological and religious basis of the construction of the Phase B Zuto: Twenty-seven stone images of Buddha have been discovered at Zuto. Their stylistic analysis suggests that the ideological basis of Zuto was mainly Buddhavatamsaka-nama-mahavaipulya Sutra 華厳経( Kegon Kyo), and also incorporates some Saddharma-pundarika Sutra 法華経 (Hoke Kyo). Since Zuto was auxiliary to Todai-ji, it is possible to imagine that the ideological and religious basis of the construction of Zuto was Buddhavatamsaka-nama-mahavaipulya Sutra, which was also the ideological and religious foundation for the erection of the colossal image of Buddha Vairocana at Todai-ji. Then, a question remains why the ideas of Saddharma-pundarika Sutra were incorporated. A hypothesis gains support that a tendency existed in the 750’s not to distinguish Buddhavatamsaka-nama-mahavaipulya Sutra and Fanwang Sutra 梵網経(Bonmo Kyo) clearly. This tendency may be apparent in the observation that illustrations based on the ideas of the Bonmo Sutra were engraved to lotus leaves that constituted a part of the seat where the Buddha Vairocana sat. It is also possible that the ideas of the Tendai 天台 Sect were respected at that time.


 This tendency was probably a result of a visit to Nara by Chinese Priest Jianzhen 鑑眞(688-763) in 754. He brought Japan numerous texts, including the Tendai Hokke Sandaibu (『天台法華三大部』 Three great books related to Saddharma-pundarika Sutra, written and compiled by Zhiyi 智顗). Researchers hypothesize that, at the occasion of Jianzhen founding a Buddhist ordination platform at Todai-ji, the fusion of vinaya and Buddhavatamsaka-nama-mahavaipulya developed into the unity of the Tendai Sect and Buddhavatamsaka-nama-mahavaipulya. On the top of the ordination platform at Todai-ji was a ranta-stupa where both Prabhutarantna Tathagata and Buddha seated. A similar emphasis of the ideas of Saddharma-pundarika Sutra at the Phase B Zuto was probably a result of this tendency at Todai-ji; it is likely that both Roben 良弁(689-773)  and Jcchu adopted the overall trend of the religious community in Nara at that time.


 Historical background of the construction of the Phase B Zuto: After the death of Empress Dowager Komyo 光明( b.701) in 760, political divisions between the party of Fujiwara no Nakamaro 藤原仲麻呂 (706-764) and Emperor Junnin 淳仁(733-765) and the party of Retired Empress Koken 孝謙(718-770) and Priest Dokyo 道鏡(?-772) became apparent. Priests Roben and other priests at Todai-ji joined the anti-Nakamaro party. At the time of Nakamaro’s rebellion, Priests Ankan 安寛(?-?), Jicchu, and others sided with the party of Dokyo. After the rebellion, Priest Jicchu produced a model case for a small temple-complex to store one million miniature pagodas. We support a hypothesis here that the construction of the upper stratum Zuto was an out come of the same intention as to produce one million miniature pagodas and to build a monastery to house them. These projects were carried out in prayer for the tranquility of the imperial court, prolonged life of the empress who did not have an heir, and the national security.


 Questions still remain to be considered: First, what made it necessary to attach the ideological significance discussed above to the Phase B Zuto? Al though the Phase B Zuto was a re-modification of the Phase A Zuto, the possibility remains that the physical structure of and ideological significance attached to the two phases of Zuto are distinctive. The re-modification might represent an act that Zuto was repainted with the current religious ideology that was dominant at Todai-ji.


 Secondly, why was it necessary to reconstruct nearly the entire structure of Zuto, rather than simple re-modification? The Phase A Zuto had numerous structural deficiencies, and was poorly constructed. It is likely that the poor structure resulted in serious troubles soon after the completion, such as the collapse of stone walls that were too high. The reconstruction of Zuto may be interpreted the same as Priest Jicchu’s other achievements of making up the poor works of the Zo-Todai-ji Shi ( 造東大寺司 Bureau of the Todai-ji Construction) that reduced and decreased the function and motivation of the Todai-ji construction.


 Historical background of the construction of the Phase A Zuto: We propose a hypothesis that the Phase A Zuto was founded by Empress Shotoku 称徳 (Retired Empress Kokon enthroned again) in prayer for the recovery from illness of the Empress Dowager Komyo, who was closely involved in Todai-ji Shin-Yakushi-ji 新薬師寺. It is likely that the image placed at the center of the eastern face of the lower stratum Zuto was Bhaisajyaguruvaiduryaprabha (Yakushi 薬師, a Buddha for healing). The construction started right before the death of the Empress Dowager Komyo. The selection of the site for the construction of this Zuto was, in terms of the direction, closely related to the locations of both Todai-ji and Shin-Yakushi-ji. Another line of evidence gives support to our hypothesis; the Phase A Zuto was not or could not be destroyed when Priest Jicchu constructed the Phase B Zuto. Since Jicchu sided with the party of Priest Dokyo and Empress Shotoku, it is inconceivable that Jicchu would destroy facilities originally built by Empress Shotoku.


 Stylistiic origins and genealogy of Zuto: A dominant hypothesis is that Zuto could be traced back to the south Asian origins. However, we would argue that the origins were Chinese pagoda constructed with tiles. Our hypothesis is based on the following lines of evidence: the method of construction featured by piling up materials rather than assembling frames; eaves not jotting out of the roofs; and, each story setting back from the lower story. All these three are of Chinese origins. It is possible that this style was adopted in lieu of a tall, wooden pagoda, in order to emphasize Chinese taste.


Chronological Table

Era Name   Year  Emperor or Empress’s Name

Wado 和銅 1   708  Gemmei 元明

Reiki 霊亀 1   715  Gensho 元正

Yoro 養老 1   717    〃

Sinki 神亀 1   724  Shomu 聖武

Tempyo 天平 1  729    〃

Tempyo-Kampo 天平感宝 1 749  Koken 孝謙

Tempyo-Shoho 天平勝宝 1 749    〃

Tempyo-Hoji 天平宝字 1 757    〃

〃 2 758  Junnin 淳仁

〃 8 764  Shotoku 称徳

Tempyo-Jingo 天平神護 1 765    〃

Jingo-Keiun 神護景雲 1  767    〃

Hoki 宝亀 1   770  Konin 光仁

Ten’o 天応 1   781  Kammu 桓武

Enryaku 延暦 1  782    〃