How were rockets used during the Mongol siege of K’ai-feng in 1232?

During the 1232 siege of K’ai-feng, Chinese defenders utilized weapons described as "arrows of flying fire." While historical records do not explicitly label these as rockets, many historians conclude they were early rocket-based weapons because the accounts do not mention the use of bows or other traditional launching mechanisms.1

These devices likely employed black powder as a propulsive charge, which increased the range of the arrows and served as an incendiary agent against the Mongol forces. Later military illustrations depict these weapons as powder rockets attached to arrows and spears. In addition to these projectiles, defenders also deployed "heaven-shaking thunder," which were explosive bombs dropped from the city walls or launched via catapult to inflict damage on the attackers.12