Long before flying boats or missions, this was - and remains - Warnumamalya country. The Anindilyakwa people organise themselves into fourteen clan groups gathered into two moieties, a web of kinship that ties every person to specific stretches of land and sea and governs who may speak for which place. Their language, Anindilyakwa, is among the most complex Aboriginal languages still spoken at home, dense with grammatical detail that has drawn linguists from around the world; on Groote Eylandt it is simply the everyday tongue, with several Yolngu Matha speakers among the community as well. The median age in Umbakumba is just twenty-five - this is a young place, where children grow up speaking their ancestral language first and English second. The Mamarika maintain their ceremonies and law, and keep close ties with relatives across the water at Numbulwar on the mainland and on Bickerton Island. According to the 2016 census the community numbered 503 people, and more than nineteen in twenty residents are Aboriginal or Torres Strait Islander - this is, overwhelmingly, an Anindilyakwa town.

From around the early to mid-1700s, fleets of Macassan sailors rode the monsoon winds south from Sulawesi to harvest trepang - the sea cucumber prized in Chinese kitchens - from these reefs. They came as visitors and traders, not colonisers, and the encounter left its mark in both directions: tamarind, chilli, and other foods entered the local table, while words and trade goods flowed back north. The contact ran for generations until the new Australian government shut it down with the White Australia Policy in 1906. The visitors are gone, but their wild tamarind trees still shade the country, and the very name of the place is a word they carried across the sea.

Fred Gray arrived in East Arnhem Land in 1932, a pearl and trepang trader who came to know the Anindilyakwa and earned their trust. In 1938 he established a settlement at Umbakumba, on an old Macassan trading site across Little Lagoon from a new flying-boat base. That base was no backwater. It served the Qantas Empire Airways flying boats on the long-haul Empire route that linked Sydney, Singapore and the south of England - a journey of days, hopping lagoon to lagoon across the globe - and the refuelling facility was leased to the Shell company. When war came, the Royal Australian Air Force took it over as a flying base, and Groote Eylandt found itself, briefly, on the front line of a world conflict.

Gray's settlement sat uneasily with the Church Missionary Society, which ran the mission at Angurugu on the western side of the island and disapproved of a private operator. In 1956 the Northern Territory Administrator informed Gray that government policy backed only recognised Christian missionary organisations, and the subsidy was withdrawn. The CMS took over the settlement administration on 17 February 1958, renaming it Umbakumba Mission under superintendent Keith Hart; by mid-1959 the Aboriginal population had grown to 175. Government welfare officers assumed control in 1966 amid staff shortages. Through every change of management, the Mamarika and their neighbours remained what they had always been: the people of this place, whose connection to it long predates the names on any administrator's letterhead.