Have you ever wondered what people in ancient times did with all those slain dragons?
I found a few answers, cited below, on the Natural History of Dragons page
from the American Museum of Natural History:

“For using dragon’s bones, first cook odorous plants; bathe the bones twice in hot water, pound them to powder and put this in bags of gauze. Take a couple of young swallows and, after taking out their intestines and stomach, put the bags in the swallows and hang them over a well. After one night take the bags out of the swallows, rub the powder and mix it into medicines for strengthening the kidneys. The efficacy of such a medicine is as it were divine!”

–Chinese medical scholar Lei Xiao (AD 420-477)

Dragon Bones

In traditional Chinese medicine, longgu, or “dragon bones,” are prescribed as a treatment for numerous ailments, from madness to diarrhea and dysentery. Most fragments and powders sold in Chinese pharmacies as dragon bone come from fossil remains of extinct mammals, unearthed from China’s renowned fossil beds.

Dragon’s Blood

Arab merchants once sailed to the Socotra Islands in the Arabian Sea to obtain resin from the fruit of the palmlike dragon’s blood tree. Dragon’s blood was once prized as a medicine in Europe and the Middle East. According to the early Roman naturalist Pliny the Elder, it formed when dragons attacked elephants, and their blood ran together and congealed.

 

American Museum of Natural History page: https://www.amnh.org/exhibitions/mythic-creatures/dragons-creatures-of-power/natural-history-of-dragons/

Dragon bone image: http://elderscrolls.wikia.com/wiki/Dragon_Bone