From 1264 to 1308, the Mongol Empire (and its successor the Yuan dynasty) made several incursions into the island of Sakhalin off the east coast of Siberia to aid their Nivkh allies against the Ainu, who had been expanding north from Hokkaido.

The Ainu put up a tenacious resistance, even launching a counter-attack on Mongol positions on the continent across the Strait of Tartary in 1297, but finally capitulated to the Mongol-led Yuan dynasty of China in 1308.

[5] As a result of the northward expansion of the Yamato people in Honshu beginning in the 7th century AD, the Emishi were slowly assimilated into the dominant Japanese culture or pushed further north to the island of Hokkaido.

[7] The proto-Ainu Satsumon followed up with an invasion into southern Sakhalin in the 11th to 12th century, leaving behind oral traditions telling how the Ainu defeated the Tonchi people there (likely the Okhotsk), and sent them fleeing north by boat.

[9] The Mongols were motivated by their worldview that heaven had bestowed them the right to rule the whole world, thus unconquered people were naturally rebels upon whom military conquest was justified.

[20] Seeking the advice of the local Udege people around Nurgan, Taxiala was told that he must wait for the strait to freeze in the winter months, then he could march his army across the ice into Sakhalin where he would find the lands of the Nivkh and the Ainu.

[25] The Mongol armies apparently reached the southern tip of Sakhalin at this time, since ramparts of a Mongol-Chinese fort dated to the 13th century were discovered at Cape Crillon.

The ramparts, called the Shiranushi earthwork (白主土城) by Japanese archaeologists, were markedly different from Ainu chashi and is the only fortification of a continental type found on Sakhalin.

[26] Japanese researcher Kazuyuki Nakamura believes that the Shiranushi site should be identified as the Guohuo fort (果夥) mentioned in the Yuan source Jingshi Dadian (經世大典, "Compendium for governing the world"), and that it was built by the Mongols to repel attempts by Hokkaido Ainu to dislodge them.

[27] To support the continual campaigns into Sakhalin, the Mongols established military-agricultural colonies near the Amur estuary around 1285, populating them with Han Chinese exiles of the newly-extinguished Song dynasty.

These falconers, which included some Nivkh, were targeted by Ainu raiders for their falcons—the feathers were an exotic trade good—and for their supplies from China due to their status as slaves of the Mongol imperial court.

Around the time of the Mongol invasions of Sakhalin, the Ainu of Tsugaru rose up against the powerful Andō clan (安東氏) of northern Japan in a war that lasted from 1268 to 1328 called the Ezo Rebellion (蝦夷大乱).

[42] Despite the commonly accepted cause of the war being trade disagreements and religious differences between the Ainu and the Andō clan,[43] Mongol action in Sakhalin might have had a hand in creating and amplifying the conflict.