Politesse
Amor Vincit Omnia
Sure. Walls, however...China had ties with Tibet for centuries. There is debate as to whether Tibet was a part of China prior to 1959 or not. The Chinese government claims that the Yuan dynasty absorbed Tibet 800 years ago. It is not surprising that they had few if any government officials there as it was extremely difficult to travel from China to Tibet.
Personally I do not believe China would have invaded Tibet if they had not wanted a buffer state between them and India.