Balhae & Unified Silla

Balhae and Unified Silla By the mid-sixth century, the Silla Kingdom had brought under its control all of the neighboring Gaya Kingdoms, a group of fortified town-states that had developed in the southeastern region of the peninsula from the mid-first century to the mid-sixth century.

Silla also effected a military alliance with Tang China to subjugate the Goguryeo and Baekje Kingdoms. Subsequently, Silla fought against Tang China when the latter exposed its ambition to incorporate the territories of Goguryeo and Baekje. Silla repelled the Chinese in 676. Then in 698, the former people of Goguryeo who resided in south-central Manchuria established the Kingdom of Balhae.

Balhae included not only people of Goguryeo, but also a large Malgal population. Balhae established a government system centered around five regional capitals, which was modeled after the Goguryeo Kingdom's administrative structure. Balhae possessed an advanced culture which was rooted in that of Goguryeo. Balhae prosperity reached its height in the first half of the ninth century with the occupation of a vast territory reaching to the Amur river in the north and Kaiyuan in south-central Manchuria to the west. It also established diplomatic ties with Turkey and Japan.

Balhae existed until 926, when it was overthrown by the Khitan. Then many of the ruling class, who were mostly Koreans, moved south and joined the newly founded Goryeo Dynasty. Silla unified the Korean Peninsula in 668 and saw the zenith of their power and prosperity in the mid-eighth century. It attempted to establish an ideal Buddhist country. Bulguksa temple was constructed during the Unified Silla period.

However, the state cult of Buddhism began to deteriorate as the nobility indulged in luxury. Also there was conflict among regional leaders who claimed authority over the occupied kingdoms of Goguryeo and Baekje. In 935, the king of Silla formally surrendered to the court of the newly founded Goryeo Dynasty.