From the day Yongzheng began implementing "Replacing Native Rule with Centralized Rule," war had already begun in the Miao Borderlands. Large numbers of Eight Banners and Green Standard Army troops were deployed into the mountains. Yet compared with the banner-filled grasslands, the green mountains and emerald valleys looked beautiful from afar, only for one to discover Impedimenta everywhere upon entering them. Cavalry and warhorses had little advantage here; the natives' poison arrows and agile movements were far better suited to the high mountains and dense forests.
There were three kinds of poison arrows. The first used herbal poison, which lost its potency after two or three months and was difficult to treat even when the injury was minor. The second used snake venom, which could remain effective for years, but only caused the skin to ulcerate and could still be treated. The third was the so-called sa poison, the greatest threat to the Qing army. It not only killed upon drawing blood, but remained potent even after years of storage. One of its raw ingredients was sap secreted by the upas tree that grew in Guangxi. This deadly poisonous tree did more than take lives. Animals struck by upas-poisoned arrows could not be eaten either, or the eater would be poisoned as well. Even burning its branches produced smoke that could blind people.
Yet a kind of bird lived in these trees, feeding on the upas tree's seeds. This was a method of plant dispersal common to many plants, but the difference was that when these birds' droppings fell to the ground, their poison seeped underground with the rain, was absorbed by the upas trees, and caused the trees to poison themselves to death. That was precisely why upas trees were so rare.
The white sap flowing from this tree's