Military action
A civil war broke out in the Emperor of Ching between 4 of the former emperor's sons. This resulted in Jian taking the throne.
The previous emperor of Ching had a lot of concubines and a lot of sons. However, his appointed heirs and favorite concubines were all either assassinated or executed. This resulted in a civil war between his non-chosen heirs. Jian swore allegiance to one of his half-brothers who was making his claim and, when that brother died in battle, took the empire for himself.