Edited sentence: For years gunpowder was used in cottage industries.It took several hundred years for gunpowder technology to reach it's peak developement.Some western Historians believe that gunpowder was not discovered in China, as travellers like Marco Polo or Giovanni di Plano Carpini mentioned seeing gunpowder in China; But the Arabs referred to potassium nitrate as snow from China, so there is still some sort of controversy on the invention of gunpowder