dou, as part of his campaign, sent his assistant ban chao to visit the xiyu (modern xinjiang and former soviet central asia) kingdom of shanshan (on the eastern edge of the taklamakan desert. (xiyu kingdoms had long submitted to north xiongnu's authority, and unable to bear the heavy taxes, had often requested that han step in and reassert suzerainty that had been established during the western han dynasty, starting with emperor wu's reign. however, they had been constantly rebuffed by emperors guangwu and ming, who judged han to be not sufficiently strong to engage in a xiyu campaign.) initially, the king of shanshan was very pleased and welcomed the han ambassadors as honored guests, but eventually the welcome faded. ban realized that north xiongnu ambassadors must have arrived. he found out where the north xiongnu ambassadors were, and, in a night raid, massacred the xiongnu ambassadors. the king of shanshan was shocked but somewhat pleased, and submitted to han suzerainty once again.