An Lushan Rebellion
When he was a young man An Lushan learned 6 non-Chinese languages. His aptitude for languages soon earned him a job as an interpreter for the Chinese Tang military. Then in 732 AD, An became friends with General Zhang Shougui. After some time the two became very close and General Zhang began treating the portly An as his son. Four years later, An was serving under Zhang in the Pinglu Army when he led a failed attacked against both the Xi and Khitan armies and was defeated. According to Chinese military law the loss required that An be sentenced to death, but before he could be executed he was given a reprieve from the Tang Chinese Emperor Xuanzong. Xuanzong found that An was very capable and he soon made him the governor of what today is called Beijing. His assignment while in Beijing was to control the nomadic tribes who were invading from their base in Manchuria.
Before long the emperor was very impressed with An. Xuanzong built him a mansion in the capital city of Changan, and dubbed him a prince. At this time An was allowed to print his own money. In 755, An learned that members of the Emperor Xuanzong court were plotting to have him removed from power. On December 16, he assembled an army of 150,000 troops and began heading south without facing any opposition. Then, just 24 days later he and his troops crossed the Yellow River and seized the Grand Canal. This brought commerce to a halt and prevented it from reaching the imperial court. Just 10 days later, An and his troops seized the first of the two Chinese capitals, the city of Luoyang. At this time he declared himself emperor.
During the summer of 756, Emperor Xuanzong made a disastrous decision. He ordered his troops to abandon their defensive positions and attack An Lushan and his army. Consequently, the Chinese National Army was defeated and Xuanzong and his consort Yang Guifei were forced to flee the other capital city of Changan. Soon afterward, Xuanzong's troops turned against him, forcing him to strangle the love of his life Yang Guifei. At this time An Lushan became gravely ill, losing his eye sight and developing boils all over his face. Unable to lead his troops, An's sons and his generals pressed on with the rebellion.
At this time An became increasingly violent, often whipping or caning his eunuch servants Li Shu'er and Yan Zhuang. Then An surprised everyone when he chose his favorite son An Qingen to become the next crown prince. This infuriated his other son An Qingxu who now believed that his life was in danger. An Qingxu decided to strike first. On the night of January 29, 757, he and Yan served as lookouts when Li Shu'er entered An Lushan's room and killed him with a sword. The next morning Yan announced that An Lushan was seriously ill and that An Qingxu was assuming the Chinese throne. Eventually, the Tang would suppress An Lushan's successors and reclaim both of capitals. However, the country was in shambles and all of their border defenses had collapsed. In 759 An Qingxu was assassinated by Shi Shiming who then assumed the throne. Four years later, Tibet would take advantage of Tang weakness and invade from the west and seize the capital city of Changan, installing their own prince on the throne. At this time the Tibetans also took control of the Silk Road.