In 630, Wen was made "Zhongshu Ling" (中書令), the head of the legislative bureau and a post considered one for a chancellor. He was also created the Duke of Yu. Earlier that year, the general Li Jing had inflicted a heavy blow to Ashina Duobi's forces, and later that year, after Ashina Duobi was captured, Eastern Tujue chieftains submitted to Tang. Emperor Taizong requested opinions on what to do with Eastern Tujue's people. There were many different opinions, but the two opinions that Emperor Taizong appeared to consider the most were the ones by Wen and Wei, who debated extensively before Emperor Taizong. Wen argued that, pursuant to precedents of what Eastern Han Dynasty did with the Xiongnu, the Eastern Tujue people should be placed within Tang borders but organized in tribal form, to serve as a defense perimeter on the northern border. Wei advocated that the Eastern Tujue people be placed north of Tang borders, believing that they would pose a threat if placed within Tang borders. Wen, however, argued that the Eastern Tujue people could eventually be assimilated and become an asset to the Tang state, and Emperor Taizong agreed with Wen. He established 10 prefectures to settle the Eastern Tujue people and made the major chieftains the prefects, while inviting a number of Eastern Tujue nobles to serve as generals at Chang'an.