Complex sentence: Envoys went back and forth between them, but because of Jahan Shah's heavy demands, an agreement coghuuld not be reached.having advanced as far as Muş, Jahan Shah had to postpone his attack ecause thronset of winter.
Split into simpler sentences: Envoys went back and forth between them, but because of Jahan Shah's heavy demands, an agreement could not be reached. Having advanced as far as Muş, Jahan Shah had to postpone his attack because of the onset of winter.