"The rebels crossed the region, pillaging and looting as they went."

I'd like to know why "as they went" was needed in this sentence.
"Pillaging and looting, the rebels crossed the region." seems to mean the same without it.

Can you make up some example sentences with this kind of structure with as (main clause + present participle + as clause)?

Question

"The rebels crossed the region, pillaging and looting as they went."

I'd like to know why "as they went" was needed in this sentence.
"Pillaging and looting, the rebels crossed the region." seems to mean the same without it.

Can you make up some example sentences with this kind of structure with as (main clause + present participle + as clause)?

Answer

It’s not needed, it’s just an embellishment of the sentence.
‘I’m now going to have a cup of coffee, looking at Italki posts as I sit here.’

Answer

Let me try to explain it in a simple manner. You know a sentence structure is  ' main person (noun) + rest of the sentence ' so here 
The rebels (the subject or noun)  crossed the region , pillaging and Looting as they went.  
I can go into details like subordinate clause and how it works but you would not need it to understand this prblm now. And after all it makes the sentence sound more beautiful and wholesome.

Any more queries , just text me. I would be more than happy to answer. 
Don't have a good day. Have a great day. 😊☺️