What might have happened to the song dynasty had handguns been invented in the 12th century rather than the 13th century

The Song dynasty (Chinese: 宋朝; 960–1279 CE) provided some of the most significant technological advances in Chinese history, many of which came from talented statesmen drafted by the government through imperial examinations.

The ingenuity of advanced mechanical engineering had a long tradition in China. The Song engineer Su Song admitted that he and his contemporaries were building upon the achievements of the ancients such as Zhang Heng (78–139), an astronomer, inventor, and early master of mechanical gears.[1] The application of movable type printing advanced the already widespread use of woodblock printing to educate and amuse Confucianstudents and the masses. The application of new weapons employing the use of gunpowder enabled the Song to ward off its militant enemies—the Liao, Western Xia, and Jin with weapons such as cannons—until its collapse to the Mongol forces of Kublai Khanin the late 13th century.

Notable advances in civil engineering, nautics, and metallurgy were made in Song China, as well as the introduction of the windmill to China during the thirteenth century. These advances, along with the introduction of paper-printed money, helped revolutionize and sustain the economy of the Song dynasty.