Unified Silla existed during the Northern and Southern States period at a time when Balhae controlled the north of the peninsula.

The term was used by general Kim Yu-sin, credited with leading many of the military campaigns to unify the Korean peninsula under Silla, in a letter he wrote to King Munmu as he lay dying.

Throughout its existence, Unified Silla was plagued by intrigue and political turmoil in its newly conquered northern territory, caused by the rebel groups and factions in Baekje and Goguryeo, which eventually led to the Later Three Kingdoms period in the late 9th century.

[9] Despite its political instability, Unified Silla was a prosperous country,[10] and its metropolitan capital of Seorabeol (present-day Gyeongju)[11] was the fourth-largest city in the world at the time.

[12][13][14][15] Through close ties maintained with the Tang dynasty, Buddhism and Confucianism became the principal philosophical ideologies of the elite as well as the mainstays of the period's architecture and fine arts.

Its last king, Gyeongsun, ruled over the state in name only and submitted to Wang Geon of the emerging Goryeo in 935, bringing the Silla dynasty to an end.

Unified Silla carried on the maritime prowess of Baekje, which acted like the Phoenicia of medieval East Asia,[16] and during the 8th and 9th centuries dominated the seas of East Asia and the trade between China, Korea and Japan, most notably during the time of Jang Bogo; in addition, Silla people made overseas communities in China on the Shandong Peninsula and the mouth of the Yangtze River.

[36] Unified Silla conducted a census of all towns' size and population, as well as horses, cows and special products and recorded the data in Minjeongmunseo (민정문서).