Koreans in Madagascar
Since every other Far East Asian major power has been chosen of the list (of which the Mongols were much more likely than any other as they made it to a few hundred kilometers away from Egypt in OTL), I will do a brief far fetched one of proto Koreans, possibly the proto Korean state of Gojoseon
http://en.wikipedia.org/wiki/Gojoseon
We really do not know a lot of the state, except it disappeared hundred years before Chinese language filtered into the peninsula. (700 BC to about 300 BC). Just a guess, but trade by ships was a big likelihood (seagoing ships were common in the Shang period of before 1200 BC, and when that dynasty fell, foreign guest peoples showed up on Kyushu, Japan, probably refugees from that affair).
Around 300 BC, Gojoseon lost significant western territory after a war with the Yan state, but this indicates Gojoseon was already a large enough state that could wage war against Yan and survive the loss of 2000
li (800 kilometers) of territory.
[10] Gojoseon is thought to have relocated its capital to the
Pyongyang region around this time.
[8]
Another choice might be one of three Chinese commanderies which did not last long, set up soon after the Gojoseon fell.
When
Gojoseon was defeated by the
Han dynasty of China in 108 BC, the northern region of the peninsula and Manchuria was occupied by the states of
Buyeo,
Goguryeo,
Okjeo,
Dongye, and other minor statelets.
Goguryeo's traditional founding date is 37 BC, but it was mentioned in Chinese records as early as 75 BC, or possibly even 2nd century BC. China installed four
commanderies in former Gojoseon territory, but three of them fell quickly to Korean resistance. Goguryeo gradually conquered and absorbed all its neighbors, and destroyed the last Chinese commandery in 313. (AD?)
A moderately sized group merchant and tradesmen offspring of Chinese emmigrants and local women find they fit in neither world, and relocated to Chedu Island, then to the not yet begun kingdom areas of Funan and Lâm Ấp (Vietnam/Thailand), which were possibly friendly and somewhat advanced. From there, to Madagascar, possibly beating the Indonesians, and almost certainly more advanced technologically. Preferrably the Chinese language was already introduced and manages to remain, to help ensure a growing civilization. The eastern rice growing areas would be a natural start, and only a single or few boats are necessary for this. Rice growing started about 800 BC in Korea.
(Madagascar is believed to have been started with a single small boatload of at most a couple dozen persons from Indonesia from 100 AD to 500 AD.)