Beijing's history indeed spans over three millennia, with its earliest recorded origins as the capital of the ancient states of Ji and Yan before the unification of China by the First Emperor in 221 BC. Over the centuries, it has been the heart of various dynasties, serving as a provincial center in the Qin and Han empires and later as the capital for the Liao, Jin, Yuan, Ming, and Qing dynasties. Today, Beijing stands as a modern metropolis that honors its rich historical tapestry, which is evident in its preserved ancient sites and cultural heritage.