Around the beginning of the ethnically Han Ming dynasty (1368–1644), China was leading the world in mathematics as well as science. However, Europe soon caught up to China's scientific and mathematical achievements and surpassed them. Many scholars have speculated about the reason behind China's lag in advancement. A historian named Colin Ronan claims that though there is no one specific answer, there must be a connection between China's urgency for new discoveries being weaker than Europe's and China's inability to capitalize on its early advantages. Ronan believes that China's Confucian bureaucracy and traditions led to China not having a scientific revolution, which led China to have fewer scientists to break the existing orthodoxies, like Galileo Galilei. Despite inventing gunpowder in the 9th century, it was in Europe that the classic handheld firearms, matchlocks, were invented, with evidence of use around the 1480s. China was using the matchlocks by 1540, after the Portuguese brought their matchlocks to Japan in the early 1500s. China during the Ming Dynasty established a bureau to maintain its calendar. The bureau was necessary because the calendars were linked to celestial phenomena and that needs regular maintenance because twelve lunar months have 344 or 355 days, so occasional leap months have to be added in order to maintain 365 days per year.