At the same time, the years of famine were also marked by a dramatic revival of illegal, private market activities. Smuggling across the border boomed, and up to 250,000 North Koreans moved to China.[55] Amartya Sen had mentioned bad governance as one of the structural and economic problems which contributed to the famine, but it seems that the famine also led to widespread government corruption, which nearly resulted in the collapse of old government controls and regulations.[56]