Literally "covering the mountains and plains"; used to describe things found in large numbers or spread as far as the eye can see.

Spread all over the hills and plains; existing everywhere in huge numbers.

corpses are strewn across the field; used as an idiom to describe a scene where a very large number of people have been killed, typically after a battle

(idiom) literally the plaintive whine of geese across the wilds; used to describe a land swarming with disaster victims or starving people, or to describe extremely difficult conditions

The bodies of those who died of hunger are strewn across the land; indicates a severe famine or great disaster.

to fill the sky and cover the land; as far as the eye can see

starving people are everywhere; a state of famine; a widespread disaster where bodies of those who died of hunger cover the land

Corpses are strewn everywhere across the land, typically describing the aftermath of a battle or natural disaster.