Abu Khalifah said: Muhammad bin Sallam said: "Nobility is only counted as that which began shortly before the Prophet (peace and blessings be upon him), reached the time of the Prophet (peace be upon him), and continued into Islam. So the house of Yemen that stood on the height of honour in Kindah is (the house of) al-Ash'ath bin Qays; their horseman (champion) among Banu Zubayd was Amr bin Ma'dikarib; and their poet was Imru' al-Qays, who was from Kindah. There is no disagreement about this."
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 648