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 "He adds that the Ming court's lack of concern for Tibet was one of the reasons why the Mongols pounced on the chance to reclaim their old vassal of Tibet and "fill once more the political vacuum in that country.". Is that enough to answer the question?
Answer: yes