At that time, the state of Qin was dominated by bronzes. Under the technical conditions at that time, although the hardness of bronze ware was not as good as that of iron, its toughness was still good. Qin Jun can make weapons for a long time, so their fighting capacity is greatly improved.
It is also nonsense that China's scientific and technological innovation did not develop after the Warring States Period. Paper-making, printing, gunpowder and three of the four great inventions all appeared after the Han Dynasty, and all the technologies that contributed so much to mankind were born in China. Before the Qing Dynasty, China's economic aggregate was far ahead of the world. It can be said that it has led the world for thousands of years. After the Renaissance in Europe, modern civilization rose and reached the forefront. But so far, Chinese civilization is still shining in the world.