The Portuguese explorer Vasco da Gama discovered the sea route to India in 1498, and thereafter Portugal built up a sizable colonial empire in Asia. While it was eventually eclipsed by other European powers, Portugal continued to rule Goa and the enclaves of Daman and Diu till 1961 - when these territories were liberated by the Indian armed forces. Thus, Portugal's colonial rule in India lasted longer than that of any other colonial power.
From 1668 to 1958, the Rupia was the currency of Portuguese territories. Under the Anglo-Portuguese treaty of 1878, coins for Portuguese territories in India were henceforth minted in the Calcutta mint of British India. The UnM Rupia of Portuguese India was the same as 1 Indian Rupee, identical in weight (11.66 grams), silver content (91.7%) and design (ruler's head on one side). The first such coins were minted in 1881 in the name of Luiz I, followed by coins in the name of Carlos I in 1901.
In 1910, Portugal became a Republic, and the design of coins changed - the head of the ruler was replaced by the head of liberty. There was a further change of design in 1935 - Liberty was replaced by the shield with coat of arms of Portugal, and one more change in 1947, when the silver content of the coins was cut to 50%.
In 1958, the Rupia was replaced by the Escudo, at the rate of 1 Rupee = 6 Escudos. Decimal coinage was also adopted together with the Escudo.
Read more about Portuguese coins here