Fort Tiracol was originally built by Maharaja Khem Sawant Bhonsle; the Raja of Sawantwadi; in the 17th century. The site chosen was a hillock on the northern (right) bank of the Tiracol River; which gave a commanding view of the Arabian sea. The fort was extensively rebuilt by the Portuguese in 1764.

In the 15th century; the Portuguese explored the sea route to India and Pope Nicholas V enacted the Papal bull Romanus Pontifex. This bull granted the patronage of the propagation of the Christian faith in Asia to the Portuguese and rewarded them with a trade monopoly for newly discovered areas.

After Vasco da Gama arrived at Calicut on the coast of Kerala in India in 1498; the trade became prosperous. In 1510; the Portuguese wrested Goa from the Sultan of Bijapur and finally established themselves in Goa. By 1544; they conquered the districts of Bardez and Salcette in Goa.

In 1534; the Archdiocese of Goa was established. Soon missionaries of the newly founded Society of Jesus were sent to Goa; which lead to conversion of many locals to Christianity. In 1542; Francis Xavier; co-founder of the Society of Jesus; arrived in Goa.