King Zhaoxiang of Qin
Because King Zhaoxiang had not yet legally come of age (traditionally at the age of 20), his mother, who was now known as Queen Dowager Xuan, became the regent. She was supported by her brothers, Wei Ran and Mi Rong (羋戎), as well as two other sons, Prince Yi (公子悝) and Prince Fu (公子巿), the four of them collectively known as the "Four Nobles" (四貴).
Duke Cheng of Qin
Duke Cheng was the second of the three sons of his father Duke De of Qin. His older brother Duke Xuan of Qin succeeded his father as ruler of Qin in 676 BC. But when Duke Xuan died in 664 BC, he passed the throne to Duke Cheng instead of one of his nine sons. When Duke Cheng died four years later, he did the same and passed the throne to the third brother Duke Mu of Qin, even though he had seven sons.