How did the Europeans learn of gunpowder?

How did the Europeans learn of gunpowder?

As the dark Ages drew to a close, there was increasing overland travel to the Far East. Merchants began sending caravans over the long, dusty roads that wound their way through the Middle East, over the mountains and into China and India. These traders must have brought back samples of the explosive compound. Many historians believe that they, like the Chinese, discovered the proper proportions of saltpeter, sulphur and carbon. Researchers of the Middle Ages had a new and powerful device. What they did not know was that gunpowder would shape the future history of humanity