Question: When did duck roasting begin in China?
About the article "Peking duck", section "History".

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Covering or uncovering a roasting pan will depend upon the type of meat being roasted, or the recipe being followed.
Generally, meat that is high in fat content, such as duck, has no need of being covered during roasting.
A lean cut of meat, however, will benefit from being covered during a long roasting time, to retain juices and soften the meat (for example, in using a tajine for roasting meat). 
The next step in the process is the roasting of the green coffee.
Coffee is usually sold in a roasted state, and with rare exceptions all coffee is roasted before it is consumed.
It can be sold roasted by the supplier, or it can be home roasted.
The roasting process influences the taste of the beverage by changing the coffee seed both physically and chemically.
The seed decreases in weight as moisture is lost and increases in volume, causing it to become less dense.
The density of the seed also influences the strength of the coffee and requirements for packaging.
The actual roasting begins when the temperature inside the seed reaches approximately , though different varieties of seeds differ in moisture and density and therefore roast at different rates.
During roasting, caramelization occurs as intense heat breaks down starches, changing them to simple sugars that begin to brown, which alters the color of the seed.
Sucrose is rapidly lost during the roasting process and may disappear entirely in darker roasts.
During roasting, aromatic oils and acids weaken, changing the flavor; at , other oils start to develop.
One of these oils, caffeol, is created at about , which is largely responsible for coffee's aroma and flavor. 
This word replaced Old English "ened/ænid" "duck", possibly to avoid confusion with other Old English words, like "ende" "end" with similar forms.
Other Germanic languages still have similar words for "duck", for example, Dutch "eend" "duck" and German "Ente" "duck".
The word "ened/ænid" was inherited from Proto-Indo-European; compare: Latin "anas" "duck", Lithuanian "ántis" "duck", Ancient Greek "nēssa"/"nētta" (νῆσσα, νῆττα) "duck", and Sanskrit "ātí" "water bird", among others.
A duckling is a young duck in downy plumage or baby duck; but in the food trade young adult ducks ready for roasting are sometimes labelled "duckling".
A male duck is called a drake and the female duck is called a duck, or in ornithology a hen. 
Ducks are medium-sized aquatic birds with broad bills, eyes on the side of the head, fairly long necks, short legs set far back on the body and webbed feet.
Males, known as drakes, are often larger than females (simply known as ducks) and are differently coloured in some breeds.
Domestic ducks are omnivores eating a variety of animal and plant materials such as aquatic insects, molluscs, worms, small amphibians, waterweed and grasses.
They feed in shallow water by dabbling, with their heads underwater and their tails upended.
Most domestic ducks are too heavy to fly, and they are social birds, preferring to live and move around together in groups.
They keep their plumage waterproof by preening, a process that spreads the secretions of the preen gland over their feathers.
Clay models of ducks found in China dating back to 4000 BC may indicate that the domestication of ducks took place there during the Yangshao culture.
Even if this is not the case, domestication of the duck took place in the Far East at least 1500 years earlier than in the West.
Lucius Columella, writing in the first century BC, advised those who sought to rear ducks to collect wildfowl eggs and put them under a broody hen, because when raised in this way, the ducks "lay aside their wild nature and without hesitation breed when shut up in the bird pen".
Despite this, ducks did not appear in agricultural texts in Western Europe until about 810 AD when they begin to be mentioned alongside geese, chickens and peafowl as being used for rental payments made by tenants to landowners.
It is widely agreed that the Mallard ("Anas platyrhynchos") is the ancestor of all breeds of domestic duck (with the exception of the Muscovy Duck ("Cairina moschata"), which is not closely related to other ducks).
Ducks are farmed mainly for their meat, eggs and down.
As is the case with chickens, various breeds have been developed, selected for egg-laying ability, fast growth and a well-covered carcase.
The most common commercial breed in the United Kingdom and the United States is the Pekin duck, which can lay two hundred eggs a year and can reach a weight of in forty-four days.
In the Western world, ducks are not as popular as chickens, because the latter produce larger quantities of white, lean meat and are easier to keep intensively, making the price of chicken meat lower than that of duck meat.
While popular in "haute cuisine", duck appears less frequently in the mass-market food industry.
However, things are different in the East.
Ducks are more popular there than chickens and are mostly still herded in the traditional way and selected for their ability to find sufficient food in harvested rice fields and other wet environments. 
In the 14th century Ming Dynasty, southern China and Japan enjoyed much cultural exchange.
Significant merchandise was traded and the roasting method of processing tea became common in Kyushu, Japan.
Since the steaming (9th century) and the roasting (13th century) methods were brought to Japan during two different periods, these teas are completely distinct from each other.