Wikipedia
Al-Hasa
Al Ahsa, El Hasa, or Hadjar ( al-Aḥsāʾ, locally al-Ahasā is a traditional oasis region in eastern Saudi Arabia whose name is used by the Al-Ahsa Governorate, which makes up much of that country's Eastern Province. The oasis is located about 60 km inland from the coast of the Persian Gulf.
Al-Ahsa is part of the region known historically as Al Bahrain geographical province in Eastern Arabia, which includes the eastern coast of the Arabian Peninsula down to the borders of Oman, and also includes the island of Awal (modern-day Bahrain). Historically, Al Ahsa was the main city in Al Bahrain province, making up most of its population and providing most of its agricultural output.