Balhae (698 – 926) (Hangul:발해, Korean pronunciation: [paɾɦɛ], Bohai [渤海] in Chinese, Бохай in Russian) was a Korean kingdom established after the fall of Goguryeo that existed during the North South states period of Korea along with Unified Silla. After Goguryeo's capital and southern territories fell to Unified Silla, Dae Jo-yeong, a former Goguryeo general, whose father was Dae Jung-sang, established Jin (振, Zhen in Chinese), later called Balhae. It was a successor state to Goguryeo.

Balhae occupied southern parts of Manchuria (Northeast China) and Primorsky Krai, and the northern part of the Korean peninsula. It was defeated by the Khitans in 926, and most of its northern territories were absorbed into the Liao Dynasty while the southern parts were absorbed into Goryeo.

The earliest extant recorded mention of Balhae come from the Old Book of Tang, which was compiled between 941 to 945. Southern Manchuria and northern Korea were previously the territory of Goguryeo, one of the Three Kingdoms of Korea. Goguryeo fell to the allied forces of Silla and the Tang Dynasty in 668. The Tang annexed much of western Manchuria, while Silla unified the Korean peninsula south of the Taedong River and became Unified Silla. In the New Book of Tang, it was recorded that the founder of Balhae, Dae Joyeong (大祚榮) was a former Goguryeo general.

Jeong Hyeon-cheol (born on February 21, 1972), better known as Seo Taiji, is a South Korean singer, musician, and songwriter. After dropping out of high school to pursue a music career, he has risen to become one of the most prominent and influential cultural icons in South Korea; many refer to him as "the President of culture". He introduced incorporating elements of popular musical genres in the United States and contributed considerably larger to Korean pop culture and Korean pop's development in the 1990s.

At an early age, Hyeon-cheol had a fascination with music. At 14, he participated in several amateur rock bands. At 17, he took the stage name of Seo Taiji when he was recruited into the metal band Sinawe, playing the bass. He chose to drop out of school because he felt that continuing to be enrolled in school would not be useful in pursuing a career in music.

Two year after Seo Tai-ji and Boys' retirement, Taiji resumed his career as a musician. His solo career has and continues to also be successful. He recurred to return to his true roots and perform rock music. Without any appearances or activity in South Korea, he released an album with a couple of music videos in 1998. There was some controversy over his sudden reversal of retirement, but his first Solo album "Seo Tai Ji" sold more than a million copies even without any promotion in Korea. His first solo work included heavy metal and Nu metal songs, but the main genre was still alternative rock. Although it was his first solo work, fans refer to it as his 5th album.