The North–South States Period (698–926 CE) is the period in Korean history when Silla and Balhae coexist in the south and north of the peninsula, respectively.After the unification wars, the Tang Dynasty established territories in the former Goguryeo, and began to administer and establish communities in Baekje.

Silla attacked the Chinese in Baekje and northern Korea in 671.

The Tang Dynasty then invaded Silla in 674 but Silla defeated the Tang army in the north.

Silla drove the Tang forces out of the peninsula by 676 to achieve unification of most of the Three Kingdoms.Korean arts flourishes dramatically and Buddhism becomes a large part of Silla culture.

Buddhist monasteries such as the Bulguksa are examples of advanced Korean architecture and Buddhist influence.

State-sponsored art and architecture from this period include Hwangnyongsa Temple, Bunhwangsa Temple, and Seokguram Grotto, a World Heritage Site.

Silla begins to experience political troubles in 780.

This severely weakens Silla and soon thereafter, descendants of the former Baekje establish Later Baekje.

In the north, rebels revive Goguryeo, beginning the Later Three Kingdoms period.

Unified Silla lasts for 267 years until, under King Gyeongsun, it is annexed by Goryeo in 935.Balhae is founded in the northern part of former lands of Goguryeo by Dae Joyeong, a former Goguryeo general.

Balhae controls the northern areas of the Korean Peninsula, much of Manchuria, and expands into present-day Russian Maritime Province.

Balhae styles itself as Goguryeo's successor state.In a time of relative peace and stability in the region, Balhae flourishes in culture, especially during the long reign of the third King Mun (r. 737-793) and King Seon.

At this time, Balhae is a culturally advanced country, so that even China refers to the Korean kingdom as "a prosperous country of the East."

However, Balhae is severely weakened by the tenth century, and the Khitan Liao Dynasty conquers Balhae in 926.Goryeo absorbs some of Balhae's territory and receives Balhae refugees, including the crown prince and the royal family, but compiles no known histories of Balhae.

The eighteenth century Joseon dynasty historian Yu Deukgong advocated the proper study of Balhae as part of Korean history, and coined the term "North and South States Period" to refer to this era.