I want to know the answer to the following question:
Who's lack of concern helped the Mongols jump at a chance to reclaim their old vassal of Tibet?
All the background I'm provided with is that "Kolmaš writes that, as the Mongol presence in Tibet increased, culminating in the conquest of Tibet by a Mongol leader in 1642, the Ming emperors "viewed with apparent unconcern these developments in Tibet."". Is that enough to answer the question?
Answer: no