David Spindler is an independent American scholar and an authority on the Great Wall of China. Writing in The New Yorker in 2007, Peter Hessler called him "a leading expert on the Wall’s history and construction." He has made more than 400 trips to the Wall. Spindler's research focuses on the Ming Dynasty, and specifically how the Wall was used at that time in response to China's northern neighbors, the Mongols, who had conquered China once and might do again.