Unified Silla, also known as Late Silla, existed from 668 CE to 935 CE, marking the unification of the Korean Peninsula under the Silla kingdom. This era began after Silla formed an alliance with the Tang Dynasty, leading to the conquest of Baekje in the Baekje–Tang War and the annexation of southern Goguryeo territories following the Goguryeo–Tang War and Silla–Tang War. Despite these conquests, Unified Silla faced political turmoil and rebellion in its northern territories, remnants of Baekje and Goguryeo, leading to the Later Three Kingdoms period in the late 9th century. The capital of Unified Silla was Gyeongju, and the government employed the “Bone Clan Class” system to maintain power, with a small elite ruling over the majority of the population.

Unified Silla was culturally and economically prosperous, known for its art, culture, and maritime prowess. The kingdom dominated East Asian seas and trade routes between China, Korea, and Japan in the 8th and 9th centuries, largely due to the influence of figures like Jang Bogo. Buddhism and Confucianism were the predominant ideologies, with many Korean Buddhists gaining fame in China. The government also conducted extensive census and record-keeping, and there was a significant emphasis on astrology and technological advancement, especially in agriculture.

However, the kingdom was not without its challenges. Political instability and intrigue were constant issues, and the elite's hold on power was threatened by internal and external forces. Despite these challenges, Unified Silla maintained close ties with the Tang Dynasty, fostering cultural exchange and learning. The era came to an end in 935 CE when King Gyeongsun surrendered to Goryeo, marking the end of the Silla dynasty and the beginning of the Goryeo period.