Stonger Northern Yuan Dynasty

So, I've been on a bit of a binge you could say regarding Mongol history and this has led me to at least one idea I find interesting for a WI/AHC here, how could you have the Northern Yuan remain a strong and united force instead of crumbling so soon following the sack of Karakorum and the death of Ayushiradar. However, I do not mean for there to be a Yuan restoration either. So basically what I'm asking is how do you avoid the emperors of the Northern Yuan merely being emperors (or khagans) in name only while the Mongols fight each other. And what would be the consequences of a stronger Mongol state that remains a threat to China and Korea and so on. There are many possibilities I find intriguing. Could the Manchus be pulled into the sway of the Mongols rather than the other way around as IOTL? How could the Ming or some other Chinese dynasty resist the continued threat of northern nomads that won't stop threatening their borders? Could Tibetan Buddhism continue to be a major influence in this alternate remnant of the Mongol Empire? One thing I'm looking for but isn't completely necessary for the TL is that the Borjigids, the descendants of Genghis Khan, remain the rulers of the Northern Yuan and preferably not as puppets, but if you can think of a better idea go ahead.

As a bonus scenario (and I imagine a much more difficult one), how could you get the 'Phags-pa script invented in the Yuan Dynasty to be used more often even after they lose their control over China?
 
I think maybe a longer struggle among the various southern Chinese factions (Zhu Yuanzhang vs. Chen Youliang, for example) could have given more time for the Northern Yuan to 'prepare' an exit from China.

A stronger Northern Yuan could have meant more 'compact' borders with the Ming, so perhaps no expansion into Gansu, Liaoning and the Ordos Loop. So these places might de-sinicize: Gansu to Tibet/Mongolia, Liaoning to Manchuria/Korea, and the Ordos to Mongolia.
 
I wonder if Chen winning in the end in his war against Zhu Yuanzhang would change things in regards to the Mongols, or if that would be plausible at all, I don't know much about the early Ming to be honest. But in any case a longer war seems like a good place to start.
 
Nah, Chen Youliang would have tried to unite China anyway. Nobody raised in that culture would have done otherwise.

Poyang was an outlier, a total victory with swift destruction of the opposing force. The Northern Yuan were unlucky in that regard.

Though in reality the Yuan was so wracked by palace coups and ineffectual monarchs at that point I doubt they would have used their breathing space wisely in any case.
 
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