Complex sentence: But instead of retreating the Tibetans showed every sign of beign there to stay, they built a fortified gate on the road that crossed Lingtu coming from Darjeeling and into Tibet, and also constructed a fort to defend it.
Split into simpler sentences: But instead of retreating the Tibetans showed every sign of being there to stay. They built a fortified gate on the road that crossed Lingtu coming from Darjeeling and into Tibet, and also constructed a fort to defend it.