In 1907 Picasso joined an art gallery that had recently been opened in Paris by Daniel-Henry Kahnweiler. Kahnweiler was a German art historian, art collector who became one of the premier French art dealers of the 20th century. He was among the first champions of Pablo Picasso, Georges Braque and the Cubism that they jointly developed. Kahnweiler promoted burgeoning artists such as André Derain, Kees Van Dongen, Fernand Léger, Juan Gris, Maurice de Vlaminck and several others who had come from all over the globe to live and work in Montparnasse at the time.