An Lushan had already made arrangements with the neighboring border nations, promising them that as soon as he ascended the throne as emperor, he would carve off and cede territories to them, along with gifts of silk and gold as compensation, provided they kept the various regional military commissioners pinned down.
Of course, verbal promises were not enough; some earnest money had to be advanced first.
Compared to the Tang Empire, the national strength of these surrounding countries fell drastically short. A tiny fraction of the wealth slipping through An Lushan's fingers was enough to drive them wild with greed.
Chapter 733