This is a brief, in a nutshell description: As per the Arabian Horse Association:

"The root stock of Sheykh Obeyd Foundation breeding is composed of 66 Arabian ancestors who were bred by, acquired by, or introduced into the gene pool by these 7 original breeders: Abbas Pasha, Ali Pasha Sherif, Ahmed Bey Sennari, Prince Ahmed Pasha Kemal, Khedive Abbas Hilme II, the Blunts (Also of Crabbet Park-England) and of the RAS (under the auspices of Dr. Branch).

Sheykh Obeyd Foundation Arabians descend in all lines from any combination of those 66 original ancestors. In addition to being Al Khamsa, all Sheykh Obeyd Foundation Arabians are Asil Club qualified, as well as Pyramid Society qualified (with the exception of the descendants of Kars)."