Hi Djungan, sorry for the slow reply… New South Wales was the original colony, and was proclaimed in 1788 northwards up to the tip of Cape York, so it did not include the Torres Strait Islands. Later Queensland split off from NSW, so it still didn’t include TSI’s. Not long before federation, Queensland annexed the Torres Strait Islands they could control the Torres Strait shipping channel, then QLD also annexed the southern half of what is now PNG (called Territory of Papua). The northern half of PNG was annexed by the Germans and became Kaiser-Wilhelmsland, which was part of German New Guinea. After the Nazi’s lost WW2, Australia took German New Guinea as spoils, and merged it with the Territory of Papua to become Papua New Guinea. It was a UN trust territory, so Australia couldn’t really keep it – so Gough Whitlam granted PNG independence from Australia, that’s when the border between PNG and Australia would have been drawn up.

Who are the TSI people and how did there come about?

The Australian border with ONG is based on Aboriginal sovereignty re 1972.