Complex sentence: After a series of failed negotiations that embittered both sides, the Jurchens attacked the Song in November 1125, dispatching one army towards Taiyuan and the other towards Kaifeng, the Song capital.
Split into simpler sentences: After a series of failed negotiations, Jin declared war against the Song in November 1125. Two armies were dispatched by the Jurchens, one towards Taiyuan and the other towards Kaifeng, the Song capital.