Bridge-building in Yunnan date back at least 1,300 years when the Tibetan Empire built an iron chain bridge over the Yangtze to the neighboring Nanzhao Kingdom at what is today Weixi Lisu Autonomous County during the Tang dynasty. Iron chain bridges are still found across high river valleys of Yunnan. The Jinlong Bridge on the Jinsha River in Lijiang remains the oldest bridge over the Yangtze.