In ancient times, Al Hasa (today's Eastern Province of Saudi Arabia) was part of Al Bahreyn and adjoined Greater Oman (today's UAE and Oman). From the second century CE, there was a movement of tribes from Al Bahreyn towards the lower Gulf, together with a migration among the Azdite Qahtani (or Yamani) and Quda'ah tribal groups from south-west Arabia towards central Oman.