 Complete the following phrase:  Chariots reached their apogee and remained a powerful weapon until the end of the Warring States Period 471221 BCE when increasing use of the crossbow, massed infantry, the adoption of standard cavalry units and the adaptation of nomadic cavalry mounted archery took over. Chariots continued to serve as command posts for officers during the Qin and Han Dynasties while armored chariots were also used by the Han Dynasty against the Xiongnu Confederation in the 