Which of the four great inventions takes the longest time?

The eastern Jin dynasty invented gunpowder; Printing (block printing) was invented in the Tang Dynasty; The compass was invented during the Warring States Period; Papermaking was invented in the Western Han Dynasty (improved in the Eastern Han Dynasty). The four great inventions refer to gunpowder, printing, papermaking and compass, which were the four great inventions of China that had a great influence on the world in ancient times.

China is the country that invented gunpowder earlier. The invention of gunpowder weapons changed the way of fighting, helped the European bourgeoisie destroy feudal fortresses and accelerated the historical process of Europe. Engraving printing was invented in the Tang Dynasty and was widely used in the middle and late Tang Dynasty, which greatly promoted the spread of culture. Compass is the result of ancient people's understanding of magnet magnetism in practice. As one of the four great inventions of ancient china, in ancient China, the compass was first used in sacrifice, etiquette, military affairs, divination, geomantic omen and other aspects to determine the orientation. It provides conditions for the navigation activities of European navigators; In the first year of Yuan Xing in the Eastern Han Dynasty (105), Cai Lun improved papermaking. This kind of paper is easy to find, cheap and of high quality, and is gradually being widely used. In order to commemorate Cai Lun's achievements, later generations called this kind of paper "Cai Hou Paper".