Xing left the Imperial Study and Rijun followed her too along with Mo Chen. Xing knew they are not here for actually preventing the war but to threaten. They do have a strong army and she had doubts that maybe Shihong is behind those tribes instigating them to form this allegiance against the Wind Kingdom. Xing had come to the conclusion that all negative events in the kingdom to be instigated by Shihong until there is definite proof that he isn't.
Also no one would come for a peaceful negotiation having fifty thousand soldiers standing by in the borders ready to attack anytime. But they probably don't know that the Wind Kingdom has been moving soldiers to the southern borders little by little for the past two months and there are actually twenty thousand of their soldiers in the borders by now. Or maybe Shihong already knows!