Silla dynasty of Silla saw a rotated monarchy with members of the Pak, Kim, and Sok families sharing the title of ruler, although not using the title of king until later As the kingdom of Koguryo was emerging as a major power in northern and central Korea, Silla was taking over tribes in the south Originally they only targeted the Saro tribe, taking tribute to the Mahan confederation as their vassal in 19 b.c.e However Silla grew dramatically in prosperity and many historians have seen this as the influence of many Chinese merchants who came to settle in the area and brought with them much resultant trade There were also influences from Japan—the envoy that took the tribute to Mahan in 19 b.c.e was of Japanese ancestry In the year after this mission, the king of Mahan died and although Silla sent over a delegation for the funeral, they rapidly drew up plans to take land from Mahan and enlarge their area In 250 c.e the Mahan confederacy, which had controlled much of central southern Korea, was finally absorbed, not by Silla, but by the kingdom of Paekche (Baekje), which had a common border with Silla This was initially thought to be dangerous as it left the Korean Peninsula under the control of three kingdoms, Silla, Paekche, and Koguryo, with little in the way of buffer states that had existed beforehand Silla and Paekche feared invasion from the emerging power of Koguryo, which had ejected the last Chinese base in 313 To counter this threat, Kim Naemul (356–401) of Silla assumed the title of maripkan or king ensured that the succession to the throne was hereditary The end of the rotating monarchy resulted in the ability to establish a more centralized administration, which adopted many of their methods of government, customs, and some Chinese culture Initially Silla sided with Koguryo to attack Paekche, which had been aiding Japanese pirates However when Koguryo moved its capital south to Pyongyang in 427, and its focus also moved south, Koguryo and Silla had to form an alliance Silla also built up trade ties with Japan King Peopheung (r 514–540) established Buddhism as the state religion of the kingdom of Silla and embarked on military expeditions that eroded the power of the nonaligned tribes in the region His successor, King Jinheung (r 540–576), enlarged the army and used it to help Paekche take lands around modern-day Seoul However in 553 he decided that his forces were strong enough to seize the whole area for itself, ending the 120year alliance of convenience between Silla and Paekche The war in 553–555 led to Silla’s massively enlarging its landholdings, with Paekche forced to cede over half of its territory This was followed by a long period of peace 371 when scholars in Silla devoted much time to Buddhism King Pak-jong, who ascended the throne in 576, abdicated to become a monk and his wife became a nun A considerable part of the wealth of the country was sent in missions of tribute to China, which weakened Silla economically but bought them a firm alliance Gradually Silla came to ally itself militarily with Tang China and in a series of lightning military campaigns, King Muyeol (r 654–661) managed to capture most of Paekche just before his death, even though the Japanese sent a fleet bringing an expeditionary force with them to help Paekche in 662 and again in 663 The war ended with Silla’s being victorious and immediately accepting Chinese overlordship Silla then persuaded China that Koguryo should be the next target, and Silla sent General Kim Yu-shin to attack Koguryo It took 10–12 years to defeat and destroy the kingdom of Koguryo, and by 668 Silla was in control of Koguryo, and this resulted in the whole of the Korean Peninsula’s being unified under the Silla, the period being known as that of the “Unified Silla.” Confident in the superiority of their soldiers after these wars, the kings of Silla became ambitious and decided to attack the Chinese soldiers on the Korean Peninsula and stop paying tribute to the Tang The first attack on the Chinese was in 671 and the Chinese responded three years later by sending in more soldiers, but the Silla not only were able to withstand the attacks, but also defeated the Chinese at Maechosong, near Yangju, and at Chonsong near the mouth of the Yseong River The Silla were also able to drive the Chinese garrison out of Pyongyang and force the Chinese soldiers to be pulled back to Liaoting Although China protested that some of the land of Paekche and Koguryo belonged to them, because of the increasing weakness at the Tang court, it was impossible to press these claims, and in 735 the Chinese formally acknowledged Silla as an independent kingdom with the rights to all the lands south of the Taedong River During the reign of King Kyongdok (r 742–764), Silla was at the peak of its power, but the Unified Silla period did not last long Initially its power was eroded by dynastic struggles King Hyegeong succeeded King Kyongdok Kim Yang-seng, who made himself King Sondok, assassinated King Hyegeong He ruled for four years and then was deposed by King Wonsong Violent court struggles and intrigue wrought havoc at the Silla court and when Sinmu became king in 839, the authority of the king had been destroyed with much of the country in the hands of nobles who formed alliances to attack other aristocrats There were many local lords