By the time Arnold and Yu Zhung returned to the makeshift command centre in Wuhan after killing all of the Minotaurs, they had a pleasant surprise waiting for them. Thanks to Xiaofan and Kang You, the tales of Arnold's strength had spread all over China like wildfire. Apparently, the Emperors whose territories shared their boundary with Wuhan had been keeping a close eye on the situation in Wuhan. Since Yu Zhung was also participating in the same event, it also attracted the attention of the other emperor's as well.
They were afraid that in the event that, Yu Zhung and Kang You were to fail in subjugating the minotaurs, they would be placed in danger and hence would have to get involved in order to get rid of the minotaurs. If all of them united, it would've been possible for them to get rid of the minotaur, without incurring heavy losses.