song dynasty in china had two parts: first part was the "north song" dynasty. it ruled most of china n time was good. it followed long time of civil wars n ppl were tired of wars. so the emperor consolidated his power n ruled over a large n stable empire.
but it grew weak n was attacked by enemies from north. it lost most of its northern territories n ruled only southern china. it was called the "south song" dynasty. due to limited resources, time was tough. it had to maintain a large army to protect against the north which required heavy taxation of ppl.