The second volume of Osprey’s New Vanguard books on medieval siege weapons is pretty much just like the first: Thompson’s gouache illustrations do a good job of showing some specific examples, while the text goes through variations on terminology and tries to make sense of them.

India probably should have just been left out of the book, as most references are ‘there’s no evidence’. The Byzantines talked about siege machinery often enough, and Islamic writers somewhat less so, but there’s very few known references to siege machines in India. In fact, all but one of the illustrated machines are from Byzantium or the Islamic world, and the one exception is surprisingly enough from Russia. That one is a little unsatisfying, as there doesn’t seem to be any indication that an idea of the size or form of the ‘fire wheel’ (other than the name) is given in the source; that said, the reconstruction given is more logical than anything I’d come up with.

India isn’t entirely absent, and there’s even a mention or two of siege machines in SE Asia, so the effort is there. In combination with the volumes on China, and Greece and Rome, Osprey has probably covered all the pre-gunpowder siege engines of the world. At least as far as scholarship has uncovered mentions of them.