Using whatever POD you believe necessary, find a way to prolong the Ming Empire of China to at least 1900 or a short time beyond that.
First thing comes into mind would be to figure out how to prevent the Manchus from becoming more powerful. Of course, the Manchus were probably the reason why the Qing dynasty first arose. Second (if this is plausible) would be to butterfly the Imjin War since China's intervention in that war must have consumed a lot of money.