In the mid-7th century, the Korean Peninsula was a stage of fierce rivalry among the Three Kingdoms: Goguryeo, Baekje, and Silla. Goguryeo, a powerful northern kingdom, successfully repelled repeated invasions from Sui and Tang dynasties, asserting its dominance in East Asia. Baekje, in turn, pressured Silla, aiming to reclaim lost territories and control maritime trade routes. Silla, isolated between these two formidable powers, sought a breakthrough for survival and growth by forming an alliance with the Tang Dynasty, known as the Silla-Tang Alliance. This was more than a simple military pact; it was a product of complex international relations surrounding the hegemony of the Korean Peninsula. The Tang Dynasty harbored ambitions to eliminate the threat of Goguryeo and subsequently dominate the entire peninsula, while Silla made a shrewd strategic decision to leverage Tang's ambitions to achieve its grand goal of unifying the Three Kingdoms. The Silla-Tang allied forces successfully conquered Baekje in 660, marking the first step towards unification. Subsequently, in 668, the allied forces brought down Goguryeo, ending the centuries-long Three Kingdoms period on the peninsula. However, contrary to their agreement, the Tang Dynasty openly revealed its ambition to control the entire Korean Peninsula. Tang established the Ungjin Commandery in the former Baekje territory and the An-dong Protectorate-General in the former Goguryeo territory. Furthermore, it even set up the Gyerim Grand Commandery in Silla's capital, Geumseong (Gyeongju), attempting to indirectly rule Silla. In response, King Munmu of Silla declared war against Tang's imperialistic ambitions to achieve an independent unification. Silla allied with Goguryeo refugees and confronted the Tang forces. Notably, in the Battle of Maecho Fortress in 675, Silla achieved a decisive victory, routing Tang's large cavalry forces and turning the tide of the war. Following this, in the Battle of Gibeolpo in 676, Silla annihilated the Tang navy, completely expelling Tang forces from the Korean Peninsula. Thus, Silla completed its independent unification of the Three Kingdoms, encompassing the territory south of the Daedong River to Wonsan Bay. Silla's unification of the Three Kingdoms holds immense historical significance as it established the first unified state on the Korean Peninsula. Although it relied on the power of an external force, the Tang Dynasty, and its territorial scope was limited to south of the Daedong River, its significance is further highlighted by its success in repelling Tang's hegemonic ambitions and achieving an independent unification. Unified Silla subsequently enjoyed approximately 300 years of stability and prosperity, fostering a brilliant national culture. It achieved unique cultural accomplishments in various fields, including the flourishing of Buddhist culture, the development of Confucian education, architecture, and art, which became important roots of contemporary Korean culture. Furthermore, it laid the foundation for establishing a distinct national identity, paving the way for the development of subsequent national states like Goryeo and Joseon. This marked a crucial turning point in shaping the historical identity and cultural heritage of the Korean people.