The Al-Hasa oasis is the largest oasis in the Kingdom of Saudi Arabia  

The Al-Hasa oasis is the largest oasis in the Kingdom of Saudi Arabia.Al-Ahsa or Al-Hasa is a traditional oasis region in eastern Saudi Arabia. The oasis is located about 60 km inland from the Persian Gulf.Al-Ahsa is part of the region known historically as Al-Bahrayn, which included the eastern coast of the Arabian Peninsula down to the borders of Oman, and also included the island of Awal.Al-Hasa has a dry, tropical climate, with a five month summer and a relatively cold winter. It enjoys the benefit of copious reserves of underground water which has allowed the area to develop its agricultural potential.
Al-Ahsa has been inhabited since prehistoric times, due to its abundance of water in an otherwise arid region.
In 899 Al-Hasa comes under control of the Qarmatian leader, al-Jannabi.
In1077The Qarmatian state of al-Hasa is overthrown, while the Qarmantians retain control of Bahrain.Comes under Ottoman control In 1818
In 1913 Ibn Saud conquers al-Hasa Oasis, annexing it into his principality of Najd.
In 1938, petroleum deposits were discovered near Dammam,resulting in rapid modernization of the region. By the early 1960s, production levels reached one million barrels per day.
It enjoys the benefits of copious reserves of underground water.