While China was never exactly fully "colonized" like it's neighbor India by the United Kingdom or Vietnam by the French, it did suffer from Western powers' insistence on unequal trading and eventually those same powers carving out territory that became sovereign to the Western countries and no longer ruled by China.
Definition of a Concession
Concessions were the lands or territories given over (conceded) to individual governments, e.g. France and Great Britain, and controlled by those governments.
In China, most concessions were located at or near ports so that the foreign countries could have easy access for trade. You've probably heard these concession names and never realized what they actually were - and might also have wondered where these places are in modern China. Furthermore, some were on "lease" to foreign powers and reverted to China within living memory as in the case of Hong Kong (from the United Kingdom) and Macau (from Portugal).
- Canton sounds familiar, right? Canton is that former Anglicized name of Guangzhou/Guangdong. Canton is the most infamous of the concessions as it was the main port of entry for much of the opium sold in China before the opening of Shanghai's concession.
- Shanghai became a foreign concession after the Opium Wars and soon after became known as the "Paris of the East". Requiring no passports for entry, Shanghai became a port-of-call for all sorts: folks hoping to make their fortune and those trying to hide from the law. Shanghai was actually divided into a number of concessions that eventually became a large concession controlled by the French and another "International" concession controlled by the British, American and quite a few other foreign powers.
- Amoy is another place name that is now a relic. Amoy is today's Xiamen in Fujian Province.
- Qingdao, formerly known as Tsingtao, was under the control of the Germans. It is they who bequeathed upon China their knowledge of brewing beer.
- Tianjin had a number of nationalities' enclaves
- Beijing had a "foreign legation" area that was opened just after the Second Opium War in the mid-1800s.
How Did Concessions Come to Be?
With the treaties signed after China's loss in the Opium Wars, the Qing Dynasty had to concede not only territory but also had to open their ports to foreign merchants wanting to trade. In the West, there was great demand for Chinese tea, porcelain, silk, spices, and other commodities. The UK was a particular driver of the Opium Wars.
At first, the UK paid China for these precious goods in silver but the trade imbalance was high. Soon, the UK began selling Indian opium to an ever-growing Chinese market and suddenly didn't have to spend so much of their silver on Chinese goods. This angered the Qing government who soon outlawed opium sales and foreign traders. This, in turn, angered the foreign traders and soon the UK along with allies sent warships up the coast and troops to Beijing to require the Qing to sign the treaties granting trade and the concessions.
The End of the Concession Era
Foreign occupation in China was interrupted by the onset of World War II and the Japanese invasion of China. Many foreigners who did not manage to escape China on Allied transport ended up interned in Japanese prison camps. After the war, there was a resurgence of expatriate immigration to China to reclaim lost property and revive business. But this period ended abruptly in 1949 when China became a communist state and most foreigners fled.