The trebuchet was first made in China
around 300 B.C. It, like the mangonel, was reinvented by the
French around the 12th century A.D. Due to its superior power and
range, it quickly replaced the mangonel on battlefields and was used
during the Crusades.
http://www.redstoneprojects.com/trebuchetstore/treb_hist_1.jpg