Simultaneously with the expedition of Leichhardt, two others were in operation, that of Sir Thomas Mitchell in the north-east of the continent, in which he traced down a considerable river, to which, in an excess of loyalty, he gave the name of Victoria, there being already a Victoria on the western coast, and which eastern river is much better called by its aboriginal name, the Barcoo; and the expedition of Sturt to ascertain the nature of the interior of the continent. Mitchell's discovery lay south-east of Leichhardt's track, and was followed up by the unfortunate Kennedy, who found another river which he named the Thomson falling into it, and traced the united stream, or channel of a stream, S.S.W. into latitude 26° 13′ 9″, longitude 142° 20′, that is, into the immediate vicinity of Cooper's Creek, with which it is, no doubt, connected, Sturt's position of Cooper's Creek being latitude 27° 46′, longitude 141° 51′.

The reason for Captain Sturt again taking the field after sixteen years of quiet domestic life, are detailed by him in the opening of his account of this expedition. He had adopted an opinion that what is now the continent of Australia, had formerly been an archipelago of islands, and that the immense plains into which not only himself, but Oxley, Cunningham, and Mitchell had descended in proceeding towards the centre of the continent had been the sea-beds of the channels which had once separated the islands.