How did the legendary Queen Yang change from a captive to a queen?

Yang rongxian (? -322), born in Cheng Nan, Taishan (now Pingyi County, Shandong Province), was the second queen of Sima Zhong, the Emperor of Jinhui. The right servant of Shangshu shot Jin Yang's granddaughter and served Yang Xuan's daughter. The Eight Kings Rebellion was abolished several times. Sima Chi, Emperor Huaidi of Jin Dynasty, was honored as the Queen of Hui Di and lived in Hongxun Palace. Yongjia Rebellion (3 1 1), Luoyang was captured by the former Zhao army, and Yang was captured as a concubine by Liu. After Liu Yao ascended the throne, he made Yang the queen, who was deeply loved and gave birth to three sons. In the first year of Yongchang (322), Yang died of illness and was buried in Ping Ling, Yu Xian. In the first year of Yongkang (300 years), Jia Nanfeng, the first queen of Jin Hui Emperor Sima Zhong, was abolished and killed by Zhao Wang Sima Lun. Sun Xiu, a favorite of Sima Lun, discussed setting up a new queen for Emperor Jinhui. Because Yang's grandfather and Sun Xiu were of the same race, and his sons also made friends with Sun Xiu, Sun Xiu made Yang the queen on the seventh day of November (65438+February 4) of the same year. Yang gave birth to a daughter, qinghe princess, for Emperor Jinhui.