Indians, that's because Zhao Qiang didn't want to say the word "India." He was worried he would be heard by the other side.
So Gao Yuan was very confused. They were clearly within Pakistan's borders now, how could there possibly be Indians here?
The country of India was historically known as Sindhu, later as Indo, and now there's no choice but to call it India, but the name isn't important. What's important is how Indians could appear within Pakistan's borders, and moreover, here in the deep rear.
As to whether these soldiers were actually Indians, Gao Yuan didn't think about it, because he felt Zhao Qiang and the others' judgment couldn't be wrong.
As for how they judged it and what they based their judgment on, Gao Yuan had no idea.
Suddenly, the officer asked, "What are you talking about?"