A major cause of the rebellion was an agrarian crisis in the north of China. Famine, along with smaller floods along the lower course of the Yellow River, forced many farmers and former military settlers to seek employment in the south, where large landowners exploited the labour surplus to amass large fortunes. The peasants also suffered from high taxation, imposed to fund the construction of fortifications along the Silk Road and garrisons against foreign infiltration and invasion. The strain led to landowners, landless peasants and unemployed veterans forming armed bands (around 170) and eventually private armies.
