The Kayardild language region includes the landscape within the local government boundaries of the Mornington Shire Council.

[7] Sometime around 1916, a man remembered only as McKenzie came to Bentinck Island and set up a sheep run, basing himself on a site at the mouth of the Kurumnbali estuary.

He would ride over the island, accompanied by a pack of dogs, and shoot any Kaiadilt man who came within sight; in local memory, he murdered at least 11 people.

They were looked down on by the Indigenous Lardil people of Mornington Island, who denied them access to the fishing grounds.

[citation needed] In the 2016 census, South Wellesley Islands had "no people or a very low population".