It took a lot of manpower to operate catapults. A fifty-man team could hurl five-pound rocks or bombs 85 yards. The largest catapults, requiring a 250-man team, could fling a 125-pound object the same distance.
Chinese were not the only ones to use catapults. When the Jurchen set siege to the Song capital of Kaifeng, the Song defenders were bombarded with rocks and gunpowder bombs flung from over a hundred catapults outside the city walls. Mongols employed Arab engineers who redesigned the catapults so that only ten men were required to hurl projectiles as large as 200 pounds. These were crucial in their five-year siege of Xiangyang, 1267-1272.