Defeat the Bandit Leader in front of you then make you way to the Bandit Lieutenant going through the center route and wait for him by the cliff near the bridge and defeat him. Afterward defeat the Bandit Lieutenant going through the top route. Head to the top right indicator to find Bao Sanniang with Guan Suo. Defeat them then head to the top left indicator to find Daqiao & Sun Ce. Defeat them then head to the bottom left indicator to find Wang Yuanji & Sima Zhao and defeat them.
Head to the Narrow Path Garrisons both will spawn 3 high defense Unit Commanders with a lot of troops around them. The West Garrison will have Zhurong & Meng Huo while the East will have Guan Yinping & Guan Ping after all troops are defeated.