pedigree of such person is traced upwards (as it invariably is) to the time of
  Mahomet, or indeed two or three generations beyond it, the details are founded
  on records of this nature, and are generally trustworthy. When genealogical
  study became the fashion, prodigious pains and learning were expended on the
  work. A Peer might as well want his armorial bearings, as a professed
  descendant of one of the early Moslems his pedigree; and rather than have
  none, it had to be invented. The contemporaries of Mahomet known by name,
  number no fewer than 9000. By the end of the first century, the genealogy of
  each one, and also of every distinguished Arab before and after, was traced up
  to his family and tribe, and thus connected with a pedigree reaching to Adam!
  Such is Arab lineage.