A Bully Named Kardesh

Kardesh, son of a political exile, bullies his way to public notice and injury. In his homeland a Chipchak clan takes royal hostages and sets off to rescue him. The Tang dynasty in China expels foreigners, making them refugees on the Silk Road.
The Gray Wolf Secret Society suborns, threatens, and murders its way toward control of an empire. Who can find its head to stop it?