The low-alcohol spirit has been distilled in Korea for hundreds of years, usually from rice or other grains. From the 1960s to 1990s, however, using rice to distill soju was banned by the South Korean government because of a nationwide shortage—but people still had to drink. So soju distillers used sweet potatoes and other starches. Some sojus, like Chamisul, are still made from sweet potatoes.