Since its foundation, Qal’at al- Bahrain served as an important business point among traders from Mesopotamia, Persia, Eastern Arabia, Central Asia and the Indus region. While the first city (ca. 2200 BC) revealed a small settlement organised on oasis agriculture, hunting and fishing, “City II” (ca. 2050 to 1750 B.C.) was a well fortified city covering a surface of 12 to 15 hectares. A group of monumental architecture, defined as a palace, prospered for several hundred years.

In the Middle Dilmun (1750- 900 BC) civilization period, the Kassites, settlers from Mesopotamia, occupied the site. Archaeological work uncovered the residence of this new governance which was probably settled in the restored palace of the former kings of Dilmun. Over a 100 cuneiform tablets in Akkadian language hold evidence of the existence of an active administration. Other interesting mechanisms found and showcased in the Site Museum are a Date Incubator used to create date syrup and a Sarcophagus in Bitumen (an oil based substance).

The Sarcophagus was used to bury people with their valuables to help them to their journey in the afterlife.
All the excavated tombs contained funerary items. As the inhabitants believed in the after life, the diseased was buried
with some of his personal belongings.
In the Late Dilmun (900 – 300 BC) civilisation, Qal’at al Bharain site prospered tremendously. For instance, excavations uncovered a luxurious architectural complex with public and private areas, a central courtyard and elaborate sanitary system. Another interesting discovery is of the more than fifty snake sacrifices that were deposited in bowls hidden beneath the floors in several areas of the palace. Moreover, a sanctuary and a zone of metallurgic workshops were recovered in the vicinity of the palace. The snake was venerated as a symbol of fertility and has some links to the Epic of Gilgamesh and his search in Dilmun for immortality. Also found are copper smelting pots which reveal a history in manufacturing traded items.

During the Hellenistic period, known as Tylos (300 BC - 600 AD), the island undergoes an exceptional phase of prosperity, apparently losing status as the island’s capital but remaining nevertheless the island’s major port as attested by the character of the finds. During the 2nd- 3rd century AD, a fortress was built north of the settlement and used as an important military administrative complex.
The Islamic period (12th to 17th century AD) saw a flurry of activity. The former coastal Tylos fortress was converted into a commercial warehouse. This commercial activity brought back the wealth of the settlement.
Following intricate political events and power changes at the end of the 13th and the beginning of the 14th centuries AD, a new fortress was erected and protected by a moat. It was however a mediocre construction which had to be constantly restored as a result of emergent Portuguese threats. In 1529, the fort could resist no longer the Portuguese artillery and hence became under the Portuguese dominion. In 1559, the fort was reinforced by 3 bastions following an attempted attack by the Ottomans.

Progressively, as the access channel to the site became too shallow, the maritime traffic was directed to Manama and Qal’at al-Bahrain site was soon abandoned. Today, it offers a peek at the glorious past of the Dilmun civilation to visitors and tourists from all over the world.