Weakened by the Rebellion of the Eight Princes and the succeeding turmoil of the Yongjia era, the Western Jin was a short-lived dynasty, but it was the establishment and later collapse of the despotic rule of 楊駿, a maternal relative as a the father Emperor Wu's empress, that served as a precursor to the political turmoil that brought the Western Jin dynasty to an end. The rise of the Yang clan as maternal relations to the throne was greatly affected by the importance placed on the court of the heir apparent in the era of Emperor Wu. The posts in the heir apparent's establishment (the grand mentor 太傅 and the junior mentor 少傅) were occupied by officials of grand councilor 宰相 rank due to the prestige accorded to the heir apparent, and the number of official in his establishment was also increased as the heir apparent grew increasingly important. Then, as a part of a policy of emphasizing maternal relations initiated by Emperor Wu circa the first year of the Xianning era (275), Yang Yao 楊珧, who was a maternal relative as a brother of Yang Jun, was installed as the supervisor of the household of the heir apparent 鯇事 and assigned to protect the heir apparent, Zhong 衷 (Emperor Hui). And in the third year of the Taikang era (282) Yang Yao's elder brother Yang Jun entered his establishment as grand protector 太保 to the heir apparent. Due to the joint appointment of officials of the Department of State Affairs 尚書省 to the core of the heir apparent's establishment after the third year of Taikang, the elevation of core officials of the heir apparent's establishment to grand councilor level was brought about. Yang Jun became a leading figure in court politics as a grand councilor along with his colleagues Ju Nan, Prince of Liang, 汝南王亮 who was made grand mentor, and Wei Guan 衞瓘, who was made junior mentor. Then, in the 10th year of the Taikang era (289) a turning point was reached as Emperor Wu fell critically ill and Yang Jun removed Ju Nan and Wei Guan and established his own despotic regime. The ascendancy of Yang Jun, described above, mainly took place by using the heir apparent as a first step, and after the accession of Emperor Hui, the heir apparent functioned as an vital point in the regime of Yang Jun. The importance placed on the heir apparent by Emperor Wu was carried out to protect the heir apparent and stabilize the dynasty, but ironically it became the breeding ground for the ascendancy of the maternal relatives and became a trigger for later political turmoil
