"The price of tea in China" is an expression which is used to denote something which is unrelated to the current topic of discussion.
This expression has stemmed from economists, who describe everything economic as affecting everything else, trying to find an expression which denotes the furthest logical connection from their current economic focus. In this way, the price of tea in China was used to denote the furthest possibility. It can also be used to denote an irrelevant topic.
It has the most common form "what does that have to do with the price of tea in China?"
There may be a second explanation.
In the 19th century the price for tea in England was the highest when the first ship with the newly harvested tea came in. So for the ship owners it was important to be as fast as possible back to England with the load, otherwise the cost of the passage was not to be recovered from the sale of the tea. Thus there were real races (the tea clipper races) where the sail ships managed to travel the whole distance from China to England in about 80 to 90 days.
The difference in prices from the first load to the later ones was so high that it was quite unimportant which price for the tea was originally paid in China. So the "price of tea in China" was something that really didn't matter for the ship owners. They had to have the tea in England as fast as possible.
We're still impressed when a person will not give something up "for all the tea in China." Recent times, however, have made this amount less impressive than in the past. In the twenty five years since the Chinese government reformed agriculture on the mainland, tea production has suffered in both quantity and quality.
This should come as a surprise to many observers. Tea almost naturally seems as though it would be one of the top success stories of Chinese agricultural reform and economic growth. Not only does it have a long legacy in China, but also its popularity is increasing dramatically around the world, making it a potentially valuable export resource. Yet, the tea industry is still troubled by finding the efficient levels of production and export that will make tea a consistently profitable commodity. Two experts, Dan Etherington and Keith Forster, have called this the "no man's land between the plan and the market."
The Chinese government changed the way agriculture was produced in the 1970s and early 1980s. Previously, farms were state owned, and farmers worked together on farming communes. The government purchased all of the harvest from the state farms at set prices. During the Chinese Reform Era, the farming communes broke down and individual households and farmers could grow their own crops on their own land. Still, not all vestiges of the old system were lost as the government contracted to buy most of the harvest output from individual farmers and continued to operate large scale farm communes through the prison system.
For most agriculture industries, the new individual household farms have brought significant gains in production and profit. The institution of household farming and the increase in market freedom prompted farmers to adjust their production activities in accordance with profit margins.
Yet, the gains are missing in the tea industry. For example, with nearly half the world's total tea gardens, China produces only about twenty percent of the world's tea output. Moreover, in 1990, China's average yield of tea per hectacre was 500 kilograms. This yield is historically low. In 1914 - 1918, Chinese tea farms yielded 900 kilograms per hectacre. This yield is also low compared to other tea producing nations. India, whose tea plantations utilize modern agriculture technology and business practices, yielded an average of 2,000 kilograms per hectacre of plucked land in 1990.