An 1884 cover sent from Taiwan to Germany achieved $385,596 at an InterAsia auction in Hong Kong on January 11-14.
It realised an increase of 99.3% against an estimate of $193,443.
The letter was sent on the day French troops landed at Keelung in northern Taiwan - the first action of the Sino-French war of 1884-1885.
It took almost six weeks for the envelope to reach Amoy on the southern coast of China due to disruption caused by the fighting.
The cover is exceptionally rare, featuring a Hong Kong 10c pair cancelled by an A/Amoy circular datestamp, along with a variety of unusual custom stamps - including a unique strike of a "Custom House/ Takow" handstamp.
A 1918 Junk one cent stationary card sent from Kiachta in Mongolia to Irkutsk in the province of Oblast, Russia sold for $326,273 - an increase of 405.9% on a valuation of $64,481. A junk is a traditional Chinese boat.
The cover is one of two known examples of Chinese stationary cards used in Kiachta, which stands on the border of Mongolia and Russia. The item features an extra three cent junk stamp with a Kiachta cancel along with an Irkutsk circular date stamp.
Another cover, sent from Taiwan to Germany in 1883, made $237,290 against a $77,377 estimate - up 206.6%.
It is the only known example sent from Taiwan to have been disinfected as a result of an outbreak of cholera in Egypt, and features two slits cut into the envelope for this purpose.
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