collective history of the Korean peninsula written together. Three constituents of the Three Kingdoms Goguryeo Goguryeo emerged on the north and south banks of the Yalu (Amrok) River, in the wake of Gojoseon's fall. The first mention of Goguryeo in Chinese records dates from 75 BC in reference to a commandery established by the Chinese Han dynasty, although even earlier mentions of "Guri" (구리) may be of the same state. Evidence indicates Goguryeo was the most advanced, and likely the first established, of the three kingdoms. Goguryeo, eventually the largest of the three kingdoms, had several capitals in alternation: two capitals in the upper Yalu area, and later Nangrang (Lelang in Chinese) which is now part of Pyongyang. At the beginning, the state was located on the border with China; it gradually expanded into Manchuria and destroyed the Chinese Lelang commandery in 313. The cultural influence of the Chinese continued as Buddhism was adopted as the official religion in 372. Goguryeo was a highly militaristic state; it was a powerful empire and one of the great powers in East Asia. The state was at its zenith in the fifth century, during the rule of King Gwanggaeto the Great and his son King Jangsu, and particularly during their campaign in Manchuria. For the next century or so, Goguryeo was the dominant nation in Manchuria and the Northern Korean peninsula. Goguryeo eventually occupied the Liaodong Plains in Manchuria and today's Seoul area. Gwanggaeto achieved a loose unification of the Three Kingdoms of Korea. Goguryeo controlled not only Koreans but also Tungusic tribes in Manchuria. After the establishment of the Sui dynasty and later the Tang dynasty in China, the kingdom continued to take aggressive actions against China, Silla, and Baekje attacks until it was conquered by allied Silla–Tang forces in 668. Most of its territory was absorbed by the Tang dynasty of China and the territory of Baekje was absorbed by Silla. Baekje Baekje was founded as a member of the Mahan confederacy. Two sons of the founder of Goguryeo are recorded to have fled a succession conflict, to establish Baekje around the present Seoul area. Baekje absorbed or conquered other Mahan chiefdoms and, at its peak in the 4th century, controlled most of the western Korean peninsula. Buddhism was introduced to Baekje in 384 from Goguryeo, which Baekje welcomed. Baekje was a great maritime power; its nautical skill, which made it