Mongol conquests (1231): Goryeo campaigns begin

Chinggis's early wars were against steppe rivals, then Western Xia and Jin. The 1215 fall of Zhongdu (Beijing) is an early named urban catastrophe in the Chinese record. Ogedei and later Mongke continued the China war; Kublai's Yuan was a conquest dynasty that also became a Chinese state.

The Khwarezm war (from 1219) after the Otrar incident produced the most famous massacre chronicles. Batu and Subutai's 1237-42 western campaign broke Volga Bulgaria and many Rus' cities and defeated European knights at Legnica and Mohi -- then withdrew when Ogedei died. Hulagu's 1258 sack of Baghdad ended the Abbasid caliphate's old political theatre.

Ain Jalut (1260) stopped the Syrian advance. Japan survived two invasion attempts (1274, 1281) that Korean and Chinese shipyards were forced to support -- a Goryeo trauma as much as a Japanese typhoon legend. Southeast Asia and Mamluk Egypt marked other edges of the project. The Golden Horde, Ilkhanate, Chagatai Khanate and Yuan were successor politics, not one forever-army. Plague in the fourteenth century later moved along some of the same routes -- a debated link, not a slogan.