The original Southern Region, formed by the split of the Liao Empire into two administrative divisions, is discussed above. It was eventually split into multiple provinces, one of which was a "new" Southern Region, with a capital at modern-day Beijing. 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. During the Jurchen invasion the Southern Region held out until 1122, under the banner of a separatist government. A Song attempt to seize the province having failed that year, Aguda invaded and captured the Southern capital without much difficulty. The Eastern Circuit consisted of the bulk of the old Kingdom of Balhae, which had originally survived within the Liao empire as a vassal state under the rule of a member of the imperial family. The capital of the original Southern Region had been located here; after the Southern Region was split the city instead became the capital of the Eastern Region and was named Dongjing. It bordered both the Kingdom of Goryeo and the Jurchen tribes, and as a result it contained a series of frontier stations and trading posts. As a result of its proximity to the Jurchen, it was the first Liao province to fall before them when they declared war. Having begun to attack border stations in 1114, they had largely completed their conquest of the Eastern Region by 1118. The Central Circuit was composed of the former territories of the Hsi, a people who, like the Balhae, had been allowed to retain a degree of autonomy after their conquest by the Khitan. Administratively this area fell under the Southern Region. Toward the end of the 10th century the central government enacted a series of measures that largely ended the Hsi's special status and fully incorporated the region into the empire. In 1006 the former residence of the Hsi king was declared to be the site of a new Central capital, which was walled in the following year. Chinese settlers moved into the capital and the surrounding lands, which were suitable for farming.