North South States Period(남북국시대, 南北國時代) refers to the period from the 7th century to the 10th century when Unified Silla and Balhae coexited at the south and the north[1], [2]. Hitherto, this period had been called the period of Unified Silla. However, scholars assert that this period must be called North South States Period of which the north state is Balhae and the south state is Silla because the unification by Silla was imperfect, and the people of destroyed Goguryeo had established Balhae. Unified Silla is the name often applied to the Korean kingdom of Silla after 668. ... Alternate meaning: Bohai Sea Balhae (Korean) or Bohai (Chinese) was a kingdom in northeast Asia from AD 698 to 926, occupying parts of Manchuria, northern Korea, and Russian Far East. ... Unified Silla is the name often applied to the Korean kingdom of Silla after 668. ... Alternate meaning: Bohai Sea Balhae (Korean) or Bohai (Chinese) was a kingdom in northeast Asia from AD 698 to 926, occupying parts of Manchuria, northern Korea, and Russian Far East. ... Silla (also spelled Shilla, traditional dates 57 BCE - 935 CE) was one of the Three Kingdoms of Korea. ... Goguryeo (traditional dates 37 B.C. â A.D. 668) was a kingdom in northern Korea and a large part of Manchuria. ...