Few places show the ambition of a lost kingdom as clearly as the valley of the Yalu at Ji'an, where Koguryo built three cities and left forty tombs that UNESCO listed in 2004. The kingdom began in the first century BC, grew into a regional power and fought off Chinese dynasties for centuries, and at its height it controlled territory from Manchuria to the middle of the Korean peninsula. Its warriors rode armoured horses, its builders cut huge blocks of granite, and its artists painted the walls of tombs with scenes that still glow.
The tombs are the most dramatic remains. The General's Tomb, a seven-tiered pyramid of granite blocks, stands on a hillside, and is often called the Pyramid of the East. It dates from the fifth century and is thought to be the burial place of King Gwanggaeto's son, or perhaps of the king himself. Nearby, a great stone stele, six metres tall, is inscribed with more than a thousand characters recording the king's conquests. The tomb murals, in the smaller chambers, show hunting, wrestling, music and mythical beasts in vibrant mineral colours.
The Yalu here is a border river, with North Korea on the far bank, and the valley is cold in winter and humid in summer. Mist in the mornings gives the hills a softness, and in autumn, the maples and birches turn yellow and red. There are signs of an old frontier everywhere: watchtowers, barbed wire, small ferries and fishermen.
A word of caution about the ride: China has strict rules about foreign motorcyclists, and you generally cannot just bring a bike across the border. Most visitors arrive by train or car or with a tour. Allow a full day to see the main sites, take water and sun protection, and bring a warm layer in the evening, when the temperature drops.