The district of Diu was ruled by many kings and dynasties, beginning the Maurya rule (c 322-220 BC) with Governor's headquarter in village Girnar near Junagarh; Emperor Ashoka rule (c 273-237 BC) when he ruled over Saurashtra through a Governor and by his descendants from Ujjain during the period 229-220 BC. The district seems to be under the rule of Indo Greek Kings Eukradites (c 171-150 BC), Menandar (c 115-90 BC) and Appollodotes II of the Ist century BC. No documented history of the district is available for the period of 150 years from the Ist century BC to about 50 AD. For more than next 1000 years, Diu formed part of the dynasties that ruled over the western India including Gujarat. The last king of the Vaja dynasty ruler of Somnath Patan ruled over Diu in the first decade of the 15th century. Between the 14-16th centuries, Diu was an important trading and naval base from which the Ottoman Turks hold the reins of maritime power.
Eearly in 1531, attempt to capture the Diu island by the Portuguese was successfully defeated by the then Sultan of Gujarat, Bahadur Shah, who was also assisted by Turkish navy. Three years later, the Portuguese invaders taking advantage of a quarrel between the Sultan and the Mughal Emperor, Humayun finally succeeded in taking over the control if Diu. The pressure exerted by both the Mughals and the Portuguese expedition led by Governor De Cunha forced Bahadur Shah to conclude a peace treaty with the Buno De Cunha on October 25, 1535, giving them actual control over the Diu Port. Forte De Mar (Fortress of Panikot) was built in 1535 by the Portuguese in the harbour. This fort was strategically important and acted as base for controlling the reins of maritime power on the north east part of the Arabian Sea.
With the weakening of Mughal power, Bahadur Shah and his successor, Sultan Mahmood II got into a conflict with Portuguese power and a new treaty was signed but again there were differences. The peace treaty signed in 1539 ceded the island of Diu and the mainland enclave of Ghoghla to the Portuguese. Finally the Governor of Goa himself arrived in full strength in 1546 and conquered Diu and Portuguese ruled there till December 19, 1961. It was separated from Goa in 1987 to become a Union Territory.