Ikkokko is a cake derived from the Chinese kong xin bing, in which a hollow center is created by wrapping bean paste with a dough and baking it. According to one school of thought its origins lie in a preserved food carried on Chinese trading ships, but during the Edo period (1603–1868) it was baked in a stove known as a hikigama, which did not exist in contemporary China, and is a sweet that evolved in a uniquely Japanese way.