After defeating Li Jue at Battle of Chang An, Lu Bu had subjugated Chang An as part of his domain. The complete annihilation of Li Jue and his army is a warning sign of not to mess with his pride. Lu Bu is now turning his attention to attack Ma Teng and claim his territory from the north. Lu Bu himself is originated from Xi Liang and he knows the warriors from Xi Liang are formidable. He sees attacking Ma Teng would provide him a decent challenge. He wants to see if his might can overcome all other formidable warriors from Xi Liang like himself.