Bai Xiaowen did not mention what he stood to gain from taking part in the Song–Mongol War. He spoke only of the threat of a nation's destruction, and that was reason enough.
Nor was he deceiving Chen Rong. The fall of the Great Song in history filled him with regret too.
Bai Xiaowen was not a nationalist, nor did he harbor especially strong ethnic feelings. But he was hostile toward the Mongols and the later Qing Dynasty. Beyond the regressive policies and ideas they imposed when they took control of the Central Plains, he could not tolerate their massacres of Han people.
A census taken in the Jin Kingdom in 1207 recorded a population of 45.81 million. Twenty-seven years later, after the Mongols destroyed Jin, only 4.75 million remained—a death rate of 90% (Shang Cheng, China Historical Outline). The Jin Kingdom had occupied Northern Song lands, and most of the people living there were Han.
When the Mongols destroyed the Southern Song, they slaughtered the inhabitants of two hundred cities. Sichuan suffered the worst of the warfare: its population fell to just 4% of its prewar level!
(This figure was calculated from the History of the Yuan: Annals of Emperor Shizu and Li Xinchuan's Miscellaneous Notes from the Court and the Wild. The details of the calculation will not be repeated here.)
Some sources recorded that the Mongols killed 200 million people worldwide—or 300 million, by another estimate. Sixty million of those deaths occurred in Song and Jin territory, and even that was a conservative estimate.
So resisting the Mongols and preserving Han rule was Bai Xiaowen's heartfelt wish. That made his words all the more persuasive when he spoke to Chen Rong.
Chen Rong thought for a long time before saying, "I understand now why you're doing this. Lu