Detailed Instructions: Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
Problem:Viewed as paranoid and dangerous, An Lushan was assassinated in 757 by his own son, An Qingxu, after which the state of Yan continued to spiral into a turmoil that eventually led to its collapse in 763.
Solution:
What noble family was An Lushan part of?