Yan Jie wasn't afraid of the spies being sent by the barbarians, because the barbarians had high noses and deep-set eyes, which were very different from their Da Ran people's black hair and black eyes. As long as they were barbarian spies, there was no chance of them not being discovered!
What Yan Jie was worried about was that these barbarians might send their slaves, people from the Zhenling Clan deep in the grasslands, to gather information. Because the Zhenling Clan, like the Da Ran people, had black hair and black eyes, if they spoke the Da Ran language, it would be impossible to tell if they were Da Ran people or not.
When Qin Shuangshuang arrived at Feiying Pass, she wasn't welcomed with open gates, but by a young general in armor, leading a formation of soldiers, ready and waiting!