Lack of technological progress in late Roman Empire

[conon394]

I read that the Chinese had the trebuchet at least 800 years (perhaps even 1,000) before it was introduced to Europe. It had far superior range, accuracy and devastating effect than any balista, catapult, or onager.

There are essentially 3 devices in question the traction trebuchet, the hybrid-traction trebuchet that added the counterweight principle, and the finally the trebuchet of your picture the counterweight-only trebuchet

The Chinese did indeed invent the traction trebuchet, but they did not invent or developed the counter-weight principle that produced the highly effective evolution in the West the ended with the counter weight only weapon. The hybrid device was likely an Arab/Islamic innovation of the 8th century.

The traction device is not anywhere near as impressive as the pure counterweight engine, and because the arm is motivated by a crew of pullers it requires a very large crew to with anything other than a small load.

From J. Needham “Science and Civilization in Chinaâ€