Adelaide is north of the Fleurieu Peninsula, on the Adelaide Plains between the Gulf St Vincent and the low-lying Mount Lofty Ranges which surround the city. Adelaide stretches 20 km from the coast to the foothills, and 94 to 104 km from Gawler at its northern extent to Sellicks Beach in the south.
The Adelaide plains were inhabited by the Kaurna tribe before European settlement, their territory extending from what is now Cape Jervis to Port Broughton. The Kaurna lived in family groups called yerta, a word which also referred to the area of land which supported the family group. Each yerta was the responsibility of Kaurna adults who inherited the land and had an intimate knowledge of its resources and features. The Kaurna led a nomadic existence within the Yerta confines in large family groups of around 30. The area where the Adelaide city centre now stands was called "Tarndanya" which translates as "male red kangaroo rock", an area along the south bank of what is now called the River Torrens. Kaurna numbers were greatly reduced by at least two devastating epidemics of smallpox which preceded European settlement, having been transported downstream along the Murray River. When European settlers arrived in 1836, estimates of the Kaurna population ranged from 300 to 1000 people.