The Southern Circuit largely formed out of a portion of the Sixteen Prefectures that had been ceded to the Liao Empire by Emperor Gao Zu of the Later Jin dynasty in 937. Over the course of the next several centuries the Song Empire continually claimed a right to this province but despite military efforts it was retained by the Liao. Due to its wealth it was at times taxed more heavily than other provinces. The region was suitable for growing rice, but the central government repeatedly banned the growing of paddy fields, likely out of a fear that the fields and the canals needed to sustain them would hinder the effectiveness of the Khitan cavalry.