This is going to be an annoying nitpick but Temujin himself never got quite that far in his own lifetime. He did annex Xi Liao already, had Xi Xia on the ropes such that they were extinguished a month after his death, and the formerly mighty Jurchen Jin Dynasty was reduced to a strip of land south of the Yellow River that would take another seven years to conquer. But the Song Dynasty which had a higher Chinese population than the aforementioned states put together was very much alive and actually grew a bit initially since it tag teamed the Jin with the Mongols. While the Song Dynasty had been extremely militarily useless and constantly humiliated by the Jin before the Mongols entered the scene, they managed to find their balls and lock in afterwards and it took a whopping fiftyish years to be subdued under all that the Mongol Empire could throw at them. They outlasted Genghis Khan’s son Ogedei Khan and his grandson Kublai Khan was already a 56 year old man by the time he felt comfortable enough to declare himself Emperor of China and kick off the Yuan Dynasty.
This is going to be an annoying nitpick but Temujin himself never got quite that far in his own lifetime. He did annex Xi Liao already, had Xi Xia on the ropes such that they were extinguished a month after his death, and the formerly mighty Jurchen Jin Dynasty was reduced to a strip of land south of the Yellow River that would take another seven years to conquer. But the Song Dynasty which had a higher Chinese population than the aforementioned states put together was very much alive and actually grew a bit initially since it tag teamed the Jin with the Mongols. While the Song Dynasty had been extremely militarily useless and constantly humiliated by the Jin before the Mongols entered the scene, they managed to find their balls and lock in afterwards and it took a whopping fiftyish years to be subdued under all that the Mongol Empire could throw at them. They outlasted Genghis Khan’s son Ogedei Khan and his grandson Kublai Khan was already a 56 year old man by the time he felt comfortable enough to declare himself Emperor of China and kick off the Yuan Dynasty.