Hua Xiong led the mounted infantry towards Yanzhou, the latest intelligence already in hand: Cao Mengde had become the Governor of Yanzhou, and then Chen Xi had already defeated the Yellow Turbans of Qingzhou. He was ordered by Chen Xi to avoid any trouble and pass through Chenliu quickly, which is why Zang Ba was sent to meet him just in case.
Of course, once Zang Ba left Mount Tai to meet Hua Xiong, it meant that the situation with Cao Mengde had taken an unfavorable turn, so unless absolutely necessary, Chen Xi hoped that Hua Xiong wouldn't utilize the cavalry led by Zang Ba. After all, the arrival of Zang Ba would equate to a fallout with Cao Cao. In such a situation that called for stability, a high-profile approach was only meant to prevent others from disrupting his plans, not to provoke war.