Xin'an County
In 640, when Emperor Taizong was about to go on a hunt in Tong Prefecture (同州, roughly modern Weinan, Shaanxi), Liu submitted a petition pointing out that it was harvest time and that the farmers would be greatly interfered with by a hunt, particularly since a good number of them would have to be conscripted to fix the roads. He asked that Emperor Taizong delay his hunt by 10 days. Emperor Taizong agreed, and praised Liu for his petition. He soon promoted Liu to be the magistrate of Xin'an County. Eventually, he was promoted to the post of imperial attendant.