# Seongdeok of Silla
Seongdeok of Silla (성덕왕) was the 33rd monarch of Silla, reigning from 702 to 737.[1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010) • [2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) His 36-year reign restored close relations with Tang China after the Silla–Tang war, distributed jeongjeon (state-granted farmland tied to taxes and service) land to the people for the first time, and fixed Silla's western border at the Pae River in 735.[1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010) • [3](https://www.kci.go.kr/kciportal/ci/sereArticleSearch/ciSereArtiView.kci?sereArticleSearchBean.artiId=ART003241228) • [2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) • [4](https://encykorea.aks.ac.kr/Article/E0029270)
| Key fact | Detail |
|---|---|
| Reign | 702–737, as the 33rd king of Silla[1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010) |
| Accession | Second son of King Sinmun; succeeded his elder brother Hyoso, who died without an heir, being raised to the throne by the hwabaek council of nobles[2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) • [5](https://db.history.go.kr/id/jo_015r_0020_0030_0110) |
| Name | Originally Yunggi (隆基), changed to Heunggwang (興光) in 712[1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010) • [5](https://db.history.go.kr/id/jo_015r_0020_0030_0110) |
| Land policy | First distribution of jeongjeon (丁田) land to the people[1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010) • [2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) |
| Diplomacy | Sent missions to Tang repeatedly throughout the reign; sources count 43, 45, or 46 of them[4](https://encykorea.aks.ac.kr/Article/E0029270) • [2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) • [5](https://db.history.go.kr/id/jo_015r_0020_0030_0110) |
| Border settlement | In 735 Tang formally granted Silla the land south of the Pae River (the Taedong River)[1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010) • [2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) |
| Death | 737, in the 36th year of his reign[2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) • [4](https://encykorea.aks.ac.kr/Article/E0029270) |
## Accession and family
Seongdeok was the second son of King Sinmun and, according to the [Samguk sagi](https://www.edgepedia.org/samguk-sagi) tradition recorded in the standard references, the full younger brother of King Hyoso.[2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) • [1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010) When Hyoso died without a son, the hwabaek council raised Seongdeok to the throne.[2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) • [5](https://db.history.go.kr/id/jo_015r_0020_0030_0110) • [6](https://m.earticle.net/Article/A261534)
The regularity of his succession is disputed. A study of the [Samguk yusa](https://www.edgepedia.org/samguk-yusa) records argues that Hyomyeong, the crown prince who became Seongdeok, and his brother fought with Hyoso for the throne, were deposed by the guk-in (the people or assembly), and became monks at Odaesan before Hyomyeong was enthroned; on this reading Hyoso and Seongdeok were half-brothers by different mothers, and Seongdeok was not the legitimate son of Queen Sinmok.[6](https://m.earticle.net/Article/A261534)
His first consort was Queen Seongjeong, daughter of Sopan Kim Wontae, married in 704 and sent out of the palace in 716; in the third month of 720 he took Queen Sodeok, daughter of Ichan Kim Sunwon, as his second queen.[1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010) • [2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674)
## Reign: policies, administration, and wars
**Domestic policy centered on farmers and officials.** To protect self-cultivating farmers, Seongdeok granted jeongjeon land modeled on Tang's equal-field system, effectively recognizing ownership of fields the people already possessed; the distribution to all the people took place in 722.[4](https://encykorea.aks.ac.kr/Article/E0029270) • [2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) He frequently inspected provinces and counties in person and granted amnesties more often than any other Silla monarch.[4](https://encykorea.aks.ac.kr/Article/E0029270) In 711 he composed the Baegwanjam (百官箴), a text instructing officials on their duties, and showed it to his ministers; late in life he issued an edict opening the way for officials to enter the [North Gate](https://www.edgepedia.org/north-gate) and offer counsel.[4](https://encykorea.aks.ac.kr/Article/E0029270) • [7](https://contents.history.go.kr/mobile/mid/hm_029_0050?tabId=e) In 722 Mobeolgun Fortress was built in the southeast to block a Japanese invasion route.[2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) • [1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010)
**Foreign policy pivoted from Japan to Tang.** Seongdeok pursued active pro-Tang diplomacy, sending missions to Tang throughout the reign; the counts differ among references, with 46 missions given by two sources, 43 by a biographical database counting from 703, and 45 by a study of the Chinese dynastic histories.[4](https://encykorea.aks.ac.kr/Article/E0029270) • [1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010) • [2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) • [5](https://db.history.go.kr/id/jo_015r_0020_0030_0110) He also sent students to study [Confucianism](https://www.edgepedia.org/confucianism).[4](https://encykorea.aks.ac.kr/Article/E0029270) Toward Tang Silla called itself a "state of gentlemen" (군자국) and toward Japan a "kingly city state" (왕성국), asserting its dignity in both directions; the official Kim Sunjeong, holding the title Sangjae, managed negotiations with Japan while the primary diplomatic target shifted from Japan to Tang.[8](https://www.kci.go.kr/kciportal/ci/sereArticleSearch/ciSereArtiView.kci?sereArticleSearchBean.artiId=ART001690343)
**Wars were fought on two fronts.** In 731, 300 Japanese ships attacked the East Sea coast and were defeated.[2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) • [5](https://db.history.go.kr/id/jo_015r_0020_0030_0110) In the winter of 733 Silla attacked Balhae at Tang's request and turned back without success.[1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010) • [2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) The campaign nonetheless produced its diplomatic reward: in 735 Tang granted Silla the land south of the Pae River, laying the basis for Silla's opening of the area north of the Yesong River.[1](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010) • [2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) • [5](https://db.history.go.kr/id/jo_015r_0020_0030_0110)
## Political influence
Seongdeok concentrated royal authority through personnel control. During his 36-year reign he replaced only three sangdaedeung (the highest state councilor) while changing the jungsi (head of the Executive Bureau) ten times; this is read as the moment that established the despotic royal authority of the Muyeol royal line.[2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674) • [5](https://db.history.go.kr/id/jo_015r_0020_0030_0110) A recent study argues that his restoration of legitimacy and of [Silla–Tang relations](https://www.edgepedia.org/silla-tang-relations) raised Silla's international standing, and that diplomatic stabilization enabled the institutionalization of Confucian governance, moving Silla–Tang relations from hierarchical subordination toward a strategic relationship of mutual interest mediated by Confucian order.[3](https://www.kci.go.kr/kciportal/ci/sereArticleSearch/ciSereArtiView.kci?sereArticleSearchBean.artiId=ART003241228) The same study concludes that the effects of his reforms were short-lived, as internal backlash against institutionalization and a loosening international order followed his death.[3](https://www.kci.go.kr/kciportal/ci/sereArticleSearch/ciSereArtiView.kci?sereArticleSearchBean.artiId=ART003241228) The irregular manner of his own accession may have been a weakness for his successors, and records of it may have been reshaped to present it as legitimate.[6](https://m.earticle.net/Article/A261534)
## End of the reign and succession
Seongdeok died in 737, in the second month of which the Japanese court discussed invading Silla.[4](https://encykorea.aks.ac.kr/Article/E0029270) • [2](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674)
## Historians' assessment
Assessment of the reign is divided. One line regards Seongdeok as a king who led Unified Silla's golden age and consolidated the despotic royal authority of middle Silla; another sees the period as a transition toward late Silla.[7](https://contents.history.go.kr/mobile/mid/hm_029_0050?tabId=e) • [8](https://www.kci.go.kr/kciportal/ci/sereArticleSearch/ciSereArtiView.kci?sereArticleSearchBean.artiId=ART001690343) A study of his Confucian governance concludes that although his reforms temporarily strengthened royal authority, their effects were short-lived.[3](https://www.kci.go.kr/kciportal/ci/sereArticleSearch/ciSereArtiView.kci?sereArticleSearchBean.artiId=ART003241228) The Samguk yusa's "Seongdeok wang" entry records welfare policy carried out through Confucian and Buddhist measures.[9](https://kiss.kstudy.com/Detail/Ar?key=4059012)
## References
1. [삼국사기 신라본기 성덕왕 (한국 고대 사료 DB)](https://db.history.go.kr/ancient/level.do?levelId=sg_008r_0040_0010)
2. [한국역대인물 종합정보 시스템 - 한국학중앙연구원](http://people.aks.ac.kr/front/dirSer/ppl/pplView.aks?pplId=PPL_3TSR_A9999_1_0005674)
3. [신라 성덕왕의 유교적 통치 질서 확립과 대당 외교](https://www.kci.go.kr/kciportal/ci/sereArticleSearch/ciSereArtiView.kci?sereArticleSearchBean.artiId=ART003241228)
4. [성덕왕 - 한국민족문화대백과사전](https://encykorea.aks.ac.kr/Article/E0029270)
5. [중국정사조선전 - 한국사 총설 DB](https://db.history.go.kr/id/jo_015r_0020_0030_0110)
6. [성덕왕의 왕위 계승 과정 검토](https://m.earticle.net/Article/A261534)
7. [성덕왕 대의 제도 및 문물 정비 - 사료로 본 한국사](https://contents.history.go.kr/mobile/mid/hm_029_0050?tabId=e)
8. [新羅 聖德王代 '上宰' 金順貞과 對日交涉](https://www.kci.go.kr/kciportal/ci/sereArticleSearch/ciSereArtiView.kci?sereArticleSearchBean.artiId=ART001690343)
9. [신라 성덕왕·효성왕대의 정치와 사회](https://kiss.kstudy.com/Detail/Ar?key=4059012)
---
*Topic: Encyclopedia › Society and history › History and archaeology › Asian history › Korea › Unified Silla and Balhae (668 to 935)*
*Initially written Sep 24, 2026 · Edited: Oct 15, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license