Aztecs Romans Germans Chinese 
Answer: Chinese
Western wheelbarrows have changed very little through the ages: a wheel way out front, a cargo space that resembles a small wagon bed, and two handles for the operator to both lift the cargo space up and push the wheelbarrow forward. It’s a very simple but quite inefficient design as the operator of the wheelbarrow is tasked with both lifting the load and pushing it forward.
By contrast, an ancient wheelbarrow design from China is radically more efficient as it uses a much larger wheel located in the center of the cargo space to completely bear the weight of the load which, in turn, leaves the operator the much less taxing task of simply steering the device. The design was easily adapted for pushing or for pulling, and the large wheel made it extremely easy to pivot the wheelbarrow in tight spaces and on narrow footpaths. The wheelbarrow was so efficient, in fact, that the Chinese did their best to keep the design a secret as it made moving military supplies and rations almost effortless.
When Westerners did encounter the design, they were universally amazed by how effective it was. In 1797, Dutch-American merchant Andreas Everardus van Braam Houckgeest described the wheelbarrows as such:
Among the carriages employed in this country is a wheelbarrow, singularly constructed, and employed alike for the conveyance of persons and goods. According as it is more or less heavy loaded, it is directed by one or two persons, the one dragging it after him, while the other pushes it forward by the shafts. The wheel, which is very large in proportion to the barrow, is placed in the centre of the part on which the load is laid, so that the whole weight bears upon the axle, and the barrow men support no part of it, but serve merely to move it forward, and keep it in equilibrium.
The design was so efficient that well into the 20th century it was used to move everything from crops, to baggage, to people, and everything in between.