In 1535, the viceroy Nuno da Cunha made a treaty with Bahadur Sah, the sultan of Khambhat, for the use of the port by Portugal.

Despite several attacks by Ottomans and Arabs, the Portuguese, who by 1541 had completed their massive fort, would remain in control of the island until 1961, when it became a union territory with Daman.

[1] The Ethiopian highlands, through the ports of Massawa and Zeila, imported Indian textiles and exported to the island slaves, wax, butter, civet and ivory.

A population of Ethiopian slaves is reported in Portuguese sources to have lived in Diu and in the neighbouring area in the early 16th century.

[2] Now a museum, the old St. Thomas Church houses antique statues, various stone inscriptions of the earlier rulers, wooden carvings and idols.

The fort was built in 1535, subsequent to a defense alliance forged by Bahadur Shah, the Sultan of Gujarat and the Portuguese when Humayun, the Mughal Emperor, waged war to annex this territory.

[4] The fort, with its double moat, is fairly well-preserved, but years of sea erosion and neglect are leading to its slow collapse.

Approximately one nautical mile (1.852 km) from the Diu jetty, it also has a lighthouse and a small chapel dedicated to Our Lady of the Sea.