Usually with a question this nebulous, it would be impossible to answer it. However, interestingly enough, the upwards of 15 invasions of Afghanistan (excepting the US invasion in 2001) were all reasoned on account of its strategic position. (There was never a desire to hold Afghanistan for its people, resources, or for religious reasons.)
The Strategic Rationale: Afghanistan is well placed at the crossroads of 4 major regions/empires: Persia in the West, China in the East, Russia/Soviet Union in the North, and India/Pakistan in the South. As a result of its central location and relatively good defensibility (Afghanistan is very mountainous), many different leaders wanted to conquer it to use its territory to conquer another one of Afghanistan's more desirable neighbors.
The United States Invasion: The US Invasion of Afghanistan in 2001 was to hunt down the terrorists responsible for the events of 9-11 (Al-Qaeda and its affiliates) and the regime that protected them.
2001
The nation that was invaded by the Soviet Union in the late 1970's was Afghanistan.
they invaded Afghanistan in 1979
Australia did not invade Afghanistan. Australia was asked to assist in getting rid of a cruel and murderous regime who supported terrorists and terrorism.
It does not invade other countries.
The USA.
april 1, 1978
So our soldiers don't get bored
September 6, 1998
Because the Americans told them too.
Afghanistan
December 24, 1979