The Ancient Tombs at Longtou Mountain are the burial sites of twelve royal figures from the Balhae (Bohai) kingdom.

It is located on Longtou Mountain, southeast of Toudao Town (头道镇) in Helong, Jilin Province, China, a region possibly called the "Western Field of the Ran Valley" (染谷之西原) by the Balhae people.

Construction on the first tombs at Longtou Mountain began sometime after 745, when King Mun moved the Balhae capital city to Junggyeong.

The discovery of Princess Jeonghyo's tombstone resolved speculation amongst scholars that the area was the former location of Hyundeok Province (顯德府) of the Balhae Kingdom.

[1] There are three burial zones:[2] The Mausoleum of Princess Jeonghyo (Chinese: Zhēnxiào Gōngzhǔ mù 贞孝公主墓, Korean: 정효공주묘) was made in 793 by the people of the early Balhae kingdom.

The burial chamber contains a 1.05-metre tall, 0.58-metre width × 0.26-m depth mugui-shaped (土圭) complete and unbroken granite epitaph, on which 728 Chinese characters, in the Regular Script style, are inscribed in 18 horizontal lines.

The Balhae scholar author of this epitaph was highly learned in the traditional Chinese literature, as reflected in the use of poetic lines modeled upon poets of the early Tang dynasty.

The gold ornament depicting a three stranded bird's wing is a piece of evidence demonstrating how Balhae was inherited of Goguryeo's crowns.