It is a noble Arab tribe, descended from former Arabian Royalty; who ruled over a sheikhdom and eventual sultanate in Najd in modern day Saudi Arabia for over 800 years continuously, prior to their banishment to modern day Iraq.
[1] The tribe was an influential one, and faced some rivalry from the House of Saud during the establishment of the first Saudi State.
The tribe migrated from Najd in Saudi Arabia circa 1750s.
[2] The Al-Obaidis descend from a branch of Zubaid who became Sultans over part of Najd prior to their defeat by Al-Saud and their banishment to Iraq.
His eldest son Sultan Obaid, is the founder of the Al-Obaidi family, and subsequent tribe.