Detailed Instructions: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: Dreyfus writes that after the Phagmodrupa lost its centralizing power over Tibet in 1434, several attempts by other families to establish hegemonies failed over the next two centuries until 1642 with the 5th Dalai Lama's effective hegemony over Tibet.
A:
Who lost their power over Tibet?