East Timor was colonised by Portugal in the 16th century and was known as Portuguese Timor until 28 November 1975, when the Revolutionary Front for an Independent East Timor (Fretilin) declared the territory's independence. Nine days later, it was invaded and occupied by the Indonesian military; it was declared Indonesia's 27th province the following year. The Indonesian occupation of East Timor was characterised by a violent, decades-long conflict between separatist groups (especially Fretilin) and the Indonesian military.