Pre-Islamic period

Inhabited since ancient times, Bahrain occupies a strategic location in the Persian Gulf. It is the best natural port between the mouth of the Tigris and Euphrates Rivers and Oman, a source of copper in ancient times. Bahrain may have been associated with Dilmun, an important Bronze age trade centre linking Mesopotamia and the Indus Valley.[11] It has been ruled by the Assyrians,[citation needed] Babylonians,[citation needed] Persians,[12] and then Arabs, under whom the island became first Christian and then Islamic.

From the 6th to 3rd century BC, Bahrain was added to the Persian Empire by the Achaemenian dynasty. By about 250 BC, the Parthians brought the Persian Gulf under its control and extended its influence as far as Oman. During the classical era, the island was known as Tylos in Europe. In order to control trade routes, the Parthians established garrisons along the southern coast of the Persian Gulf.[13] In the 3rd century, Ardashir I, the first ruler of the Sassanid dynasty, marched on Oman and Bahrain, where he defeated Sanatruq the ruler of Bahrain.[14] At this time, Bahrain comprised the southern Sassanid province along with the Persian Gulf's southern shore.[15]

The Sassanid Empire divided their southern province into the three districts of Haggar (now al-Hafuf province in Saudi Arabia), Batan Ardashir (now al-Qatif province in Saudi Arabia) and Mishmahig (which in Middle-Persian/Pahlavi means "ewe-fish").[14] Early Islamic sources describe the country as inhabited by members of the Abdul Qais,[16] Tamim, and Bakr tribes who worshipped the idol Awal, from which the Arabs named the island of Bahrain Awal for many centuries. However, Bahrayn was also a center of Nestorian Christianity, including two of its bishoprics.[14]