The Han Dynasty (206 BC–AD 220) was the second dynasty that ruled a unified China after the Qin Dynasty (221–206 BC). It saw a short interruption when the throne was usurped by Wang Mang and later fell to Liu Xuan. Historians usually use this interruption to divide the dynasty into two periods: Western (Former) Han (206 BC–25 AD) with Chang'an as its capital and Eastern (Later) Han (25–220) with Luoyang as its capital.