This large, natural harbour on the East Coast of the Northern Emirates has been an important site of maritime trade and settlement since the pre-Islamic era. Although we have some slight information, mainly from tombs, of settlement during the later 2nd millennium and early first millennium BC, contemporary with such sites as Shimal, Tell Abraq and Rumeilah, and of scattered occupation during the period of al-Dur and Mileiha, it is in the period just prior to and after the coming of Islam that we hear most about Dibba. Under the Sasanians and their Omani clients the Al-Julanda, an important market was held at Dibba. According to Ibn Habib, 'merchants from Sind, India, China, people of the East and West came to it'.
Soon after the death of Muhammad (PBUH) a rebellion broke out at Dibba and a faction of the Azd, led by Laqit b. Malik Dhu at-Taj, rejected Islam. According to one tradition, Laqit was killed by an envoy of the caliph Abu Bakr in what may have been a relatively small struggle, while other sources, including al-Tabari, say that no fewer than 10,000 rebels were killed in one of the biggest battles in the ridda (apostasy) movement. The plain behind Dibba town still contains a large cemetery which, according to local tradition, represents the fallen apostates of Dibba.
During the time of the Abbasid caliph Al Mu'tadid (870-892), a great battle was fought at Dibba during the conquest of Oman by the Abbasid governor of Iraq and Bahrain,Muhammad bin Nur. Thereafter, references to Dibba in the historical literature are scarce until we come to the Portuguese, who built a fortress there. Dibba (Debe) appears in the list of southeast Arabian placenames preserved by the Venetian jeweller Gasparo Balbi in 1580, and depictions of its Portuguese fort can be found in several sources, such as Cortesao's Portugalliae monumenta cartographica.
Around 1620-21 the Italian traveller Pietro Delle Valle, while staying with the Sultan of Bandar Abbas, met the son of the ruler of Dibba who was visiting. From this he learned that Dibba had formerly been subject to the kingdom of Hormuz, but were at that time loyal to the Safavids who, in 1623, sent troops to Dibba, Khor Fakkan and other ports on the southeast coast of Arabia in order to prepare for a Portuguese counter-attack following their expulsion from Hormuz (Jarun). In fact, the Portuguese under Ruy Freire were so successful that the people of Dibba turned on their Safavid overlords, putting them all to death, whereupon a Portuguese garrison of 50 men was installed at Dibba. More Portuguese forces, however, had to be sent to Dibba in 1627 as a result of an Arab revolt. Curiously, two years later the Portuguese proposed moving part of the Mandaean population of southern Iraq, under pressure from neighbouring Arab tribes, to Dibba. Although Dibba was offerred to the Mandaeans, they were wise enough to see that the Portuguese force there would be insufficient to guarantee their security and, while a few Mandaeans tested the waters by moving to Muscat, most returned to Basra in 1630.
In 1645 the Portuguese still held Dibba but the Dutch, searching for potential new sites for commercial activities, sent the Zeemeeuw to explore the Musandam peninsula between Khasab, on the Gulf side, and Dibba, on the East Coast. The captain of the Zeemeeuw, Claes Speelman, made drawings in his log book including what is certainly the earliest depiction of Dibba in a European source. Within a year or two, however, the Portuguese were forced out of Dibba and held only Khasab and Muscat, which they finally lost in 1650.
Eleven years later, Jacob Vogel's description of the east coast of the Oman peninsula, prepared for the VOC in 1666, contained the following: 'Dabba (which we were unable to visit because of calm and counter currents) is a place (according to the interpreter assigned to us) with about 300 small houses constructed from branches of date trees...During the days of the Portuguese there were here 4 fortresses of which the biggest one is still standing. This place also has a valley with a lot of date trees under which there are water wells, where one can get fresh water. At the Northern side of Dabba there is a small fresh water river where the fishermen live'.