A Crisis of Leadership in the Three Kingdoms and China
In 1395 Satto, the Ruler of the middle kingdom Chuzan, died at age 75 and his son Bunei took over. Also, that same year, the lord of Hokuzan died. The Lord of Nanzan died just three years later in 1398.
As part of the Chinese tribute system, the new rulers of each kingdom sent requests to Ming China asking for recognition as the new monarch. However, nothing happened for several years because the emperor of China also died in 1398. As a result, China itself was in a power struggle internally for control of the Chinese empire.
The Rise of Sho Hashi in Chuzan
Bunei continued to rule as King of Chuzan. But without having the formal endorsement of China, he was in a weakened political position. The aji he ruled over had time to reconsider their alliances and loyalties. This occurred despite Bunei’s continuation of trade with China and economic development of Okinawa.
One of those aji, a young able man named Sho Hashi, persuaded several of Bunei’s followers to switch allegiances. Together with them, he led a rebellion against Bunei. In 1402 Sho Hashi succeeded in taking the Lord of Azato’s territory, which was next to Bunei’s headquarters in Urasoe.
In 1405 Bunei finally heard from China. A new Chinese emperor had gained power and immediately sent a response to Bunei asserting that Bunei was king. But it was too late for Bunei. The opposition had gained too much energy. Sho Hashi and his forces were preparing to seize all of Chuzan.
Sho Hashi Conquers Chuzan
Sho Hashi continued to gain strength and aji loyalties after his defeat of Azato. In 1407, he launched an assault against Bunei and drove him out of Urasoe, thereby overthrowing him. Following his victory, Sho Hashi immediately sent his own tribute ship to China requesting that his father be made king, a calculated political move to win favor with the Chinese. Sho Hashi held the real power. His father served merely as a figurehead to appeal to the Confucian sense of patriarchy. The Chinese responded favorably to his request in 1408, and made his father king. Sho Hashi, for all practical purposes, was the true ruler.
Seven years later the China government also approved Nanzan’s tribute request for recognition, but Nanzan was torn apart by internal power struggles of its own.
Chuzan and the Balance of Power
Sho Hashi viewed Hokuzan as a military threat to him due to their stronghold at Nakijin castle. They were not particularly competitive against Chuzan in commercial trade or foreign relations.
He viewed Nanzan as much more of a political and commercial threat to Chuzan. Nanzan had favorable harbors for trading as did Chuzan, and was second in power to Chuzan economically.
Sho Hashi made plans to consolidate his power. He would once again use the defection of opposition aji to his side to implement his plan.
Sho Hashi Conquers and Reunites the Kingdom
Sho Hashi’s first target was Nakijin castle in Hokuzan in order to secure his military superiority first and foremost. He succeeded in winning the allegiance of some key aji supporters of the Hokuzan king in the Northern provinces. They defected to his camp. Nanzan at the time was weakened due to their own internal problems. Perhaps sensing an opportunity, Sho Hashi attacked the Hokuzan capital of Nakijin castle in 1416 and overthrew the King of Hokuzan, who committed suicide.
In 1422, Sho Hashi’s father died and Sho Hashi officially became king. He appointed his brother as warden of Hokuzan.
In 1429 the Lord of Nanzan died, and a power struggle ensued in Nanzan. Sensing Nanzan's weakness, Sho Hoshi seized the moment and launched a campaign against that territory. He successfully conquered the southern area and overthrew the Nanzan rulers. In so doing, he unified Okinawa into a true single Ryukyu Kingdom.
Thus began the First Sho Dynasty of the Ryukyu Kingdom.