Why are most of Australia's cities on eastern and southern coast of the country?​

Explanation:

The main reason is that most of Australia's interior is too dry, with extreme weather conditions, to sustain large cities and big populations. The big rivers flow across these coasts.

early settlements on the subcontinent. both the indus and the ganges rivers carried rich silt from the mountains to the plains. when the rivers flooded, the silt spread over the plains and made the soil in the river valleys fertile for farming.