 After the collapse of the Tang dynasty in 907, the Five Dynasties and Ten Kingdoms period thus ensued.Due to the decline of Tang central authority after the An Lushan Rebellion (755–763), there was growing tendency to superimpose large regional administrations over the old districts and prefectures that had been used since the Qin dynasty (221-206 BC).These administrations, known as circuit commissions, would become the boundaries of the later Southern regimes; many circuit commissioners became the emperors or kings of these states.