The Chinese were using unmanned hot air balloons from about the third century BC. One ancient story claims that the military strategist Zhuge Liang (also known as Kongming) sent a sky lantern into the sky to call for help when he was surrounded in battle. As a result (or possibly because the lanterns resemble the hat in which he is often depicted) they came to be known as Kongming lanterns. It would be perfectly possible to build a manned hot air balloon using ancient materials, but there is not a great deal of evidence to sustain the theory that this happened. We do, however, have at least one mention in an old document that the Chinese had ‘solved the problem of aerial navigation’, which might suggest that they did also send manned balloons into the air.
It is also worth mentioning the artworks depicting creatures on the Nazca plain, which were created by the Nazca culture between AD 500 and 900. The size of these artworks means that they are difficult to view in their entirety from any point on the ground, but they can be observed to spectacular effect from the air. Some have argued that this proves the Nazca had a means of flying, and had thus independently invented the hot air balloon. (Although we should also note that the artworks have also been advanced as proof that earth was colonized by ‘ancient astronauts’ from another planet, so we should be careful about leaping to any wild conclusions.)
Aerial view of geoglyphs near Nazca, Peru.