He was a member of the royal clan, the founding lineage head of the state of Yan, and elder of the minor polity Shao (召國).
The earliest biography of Lord Shao, in Sima Qian's Records of the Grand Historian, states merely that he was a member of same ancestral temple kinship group as the house of Zhou.
[4] Maria Khayutina, writing in 2015, reads the Gu Ming (顧命) chapter of the Shangshu as ordering the lineages who visit the ailing King Cheng of Zhou by their seniority rank within the Ji ancestral temple.
[4] The preceding Shang dynasty had handled succession by distributed agnatic seniority,[6] a pattern which followed would have put the Duke of Zhou next in line for the throne.
An illegally excavated manuscript version of a chapter of Shangshu, part of the Tsinghua bamboo slips, allows for the reading that the Duke of Zhou had performed a sacrifice to the ancestral spirits to divine whether he was their chosen successor to the ailing King Wu.
[9] In any case, the son of the vanquished Shang king and affiliated groups, possibly aided by Zhou royal brothers,[b] took the opportunity to rebel in an action called the Rebellion of the Three Guards.
With the violence quelled, King Wu's son, now three years less young, along with the victorious Lord Shao and Duke of Zhou, entered into a triple alliance, sharing power delicately between them.
Lord Shao was given power over the lands to the west of the twin capitals Feng and Hao, on the Wei river in present-day Xi'an, Shaanxi.