In medieval Japan, people employed several methods to increase their farmable land. One of the most significant techniques was the use of terraces, which allowed them to cultivate hilly or mountainous areas that would otherwise be unsuitable for farming. This method maximized arable land by creating flat surfaces on slopes for rice and other crops.
Additionally, they often cleared forest areas to expand agricultural land, transforming wooded regions into fields for cultivation. This deforestation was a common practice in many parts of Japan during this period.
Though they did grow barley and raised animals, those practices were more about diversification of agriculture rather than directly increasing the amount of farmable land. Overall, terraces and forest clearing were the primary methods for increasing cultivable land in medieval Japan.