Джувейни
According to Ata-Malik Juvayni during the assault on the Alamut Assassins fort, "Khitayan" built siege weapons resembling crossbows were used. "Khitayan" meant Chinese and it was a type of arcuballista, deployed in 1256 under Hulagu's command. Stones were knocked off the castle and the bolts "burnt" a great number of the Assassins. They could fire a distance around 2,500 paces. The device was described as an "ox's bow". Pitch which was lit on fire was applied to the bolts of the weapon before firing. Another historian thinks that instead gunpowder might have been strapped onto the bolts which caused the burns during the battle recorded by Juvayini.