Short answers, pulled from the story.
Remains of domestic donkeys dating to the fourth millennium BC have been found in Ma'adi in Lower Egypt. Donkeys were probably first domesticated by pastoral people in Nubia long after cattle, sheep, and goats had already been tamed.
As of 2017 however the Chinese population dropped to just 3 million due to market pressures. The world population fell from 43.7 million to 43.5 million between 1995 and 2000 before reaching 41 million in 2006.
Working donkeys in the poorest countries have a life expectancy of 12 to 15 years compared to 30 to 50 years in prosperous nations. They may be ridden used for threshing raising water or milling grain.
In 2019 The Donkey Sanctuary warned the global population could be reduced by half over the next five years because of rising ejiao demand. African countries including Uganda Tanzania Botswana Niger Burkina Faso Mali and Senegal banned China from buying their donkey products.
The earliest documented donkey hybrid was the kunga used as a draft animal in Syrian and Mesopotamian kingdoms during the second half of the third millennium BCE. These creatures were produced at a breeding center called Nagar modern Tell Brak and sold as status symbols pulling battle wagons.