The title 'Xinling' refers to Wei Wuji's fief in Xinling (present day Ningling County in Henan), which was awarded to him by his half brother King Anxi on the death of their father in 277 BC.
The concept of house guests (門客) refers to a social institution during the period when aristocrats would provide food and lodging to talented men and use them as retainers.
Lord Xinling, famed for his readiness to provide for talented men, had three thousand retainers in his service at its peak.
Xinling returned and repulsed a greater Qin force with the help of other allies such as Yan, Zhao, and Chu.
They did it in a convincing manner employing a corrupt insider (senior noble) and tricking the Crown Prince of Wei, who was a prisoner in Qin.