Yong crown prince; he created his brothers and his other sons imperial princes. He initially created Northern Zhou's Emperor Jing the Duke of Jie, but soon slaughtered all grandsons of Yuwen Tai, and eventually put the Duke of Jie to death as well. He entrusted most of the important governmental matters to his officials Gao Jiong, Yang Su, and Su Wei. Agreeing with some officials' assertions that Northern Zhou fell because its imperial princes lacked power to protect the central government, he sent his sons out to key provinces with broad powers. He further commissioned the official Pei Zheng () to carry out a project of simplifying the penal code and decrease the penalty from the harsh laws—a reform that was later largely accepted by the succeeding dynasties. Emperor Wen did not maintain as submissive a relationship with the Göktürks, which brought resentment from the Göktürks' Ïšbara qaγan Ashina Helu. The qaγan's wife, the Xianbei princess Qianjin, Yuwen Zhao's daughter, particularly hated Emperor Wen for destroying the Northern Zhou. Ashina Helu therefore carried out a series of border attacks against Sui, allied with Gao Baoning (), the former Northern Qi general who was still holding Ying Province (營州, roughly modern Zhaoyang, Liaoning). In response, under advice from the general Zhangsun Sheng (), Emperor Wen carried out the strategy of placating Ashina Helu's subordinate qaγans—his uncle Datou Khan Ashina Dianjue (), cousin Abo Khan Ashina Daxianbian (), and brother Ashina Chuluohou () – to create dissension within the Göktürks, and gradually, the strategy worked, causing the Göktürks to be unable to take unified actions against Sui. In 581, Emperor Wen commissioned a major attack on Chen, and while it was initially successful, Emperor Wen withdrew the attack in spring 582 after hearing that Emperor Xuan of Chen had died and believing it wrongful to attack a state whose emperor had just died. In 582, believing that Chang'an was too small of a city, Emperor Wen built a new capital nearby, which he named Daxing, and in spring 583 he moved the capital to Daxing. (From that point forward, Daxing and Chang'an became interchangeable names, although by the time of succeeding Tang Dynasty, the new capital was known again just as Chang'an.) Also in 582, Emperor Wen, thankful for the refusal by the vassal Emperor Ming of Western Liang to support Yuchi Jiong in 580, withdrew his forces from Western Liang's capital