Changes

During the Shang Dyansty (1600-1000 BCE), researchers have stated the climate became generally warmer. However, there were periodic cooling and likely drier conditions in eastern China. At around 1100 BC, the Shang became weaker as they had to deal with more harvest failures. However, the Shang could have adapted to this and may have withstood such change. Rather, the Zhou, who conquered the Shang and who lived west of the Shang, may have invaded as they felt their societies faced greater threats due to cooling conditions. In effect, the invasion and bellicose nature of the Zhou could be attributed to changing conditions that led to more difficult harvests for them. The concept of the Mandate of Heaven, which formulated that a Chinese dynasty should maintain order in the world, including natural orderaffecting farming and the environment, may have developed at this time as a way to legitimise rulers. It could also be used to blame rulers as climate conditions became more difficult, where rulers of China should upkeep the Mandate of Heaven. This could have happened as the Zhou justified their rule due to the failings of the Shang, as conditions became more difficult. After the cooling at around 1100BCE, climate likely returned to more favourable conditions and the Zhou may have become the long-lived dynasty in Chinese history in part due to more favourable conditions. The Zhou portrayed themselves as bringers of stability, where during the 1st millennium BCE climate conditions did generally become stable.<ref>For more on the Shang and Zhou rivalries, see: Marks, R. (2012). <i>China: its environment and history</i>. Lanham, Md: Rowman & Littlefield.</ref>

Nevertheless, long-term warmer conditions lasted did last until about 350 CE, covering nearly eight dynasties and ending around the Six Dynasties period. During warmer periods, citrus, such as oranges, may have made their way to China and began to be incorporated into diets. Subtropical herbs and spices were also likely introduced in period periods when warmer conditions prevailed, as these plants were more easily grown in northern regions that allowed the major centres of China, such as the city of Chang'an in the Han Dynasty. After 350 CE, much colder conditions became evident in northern China, with much harsher winters. This may have led to the development of ice houses for the first time, which allowed better preservation of food over the winter periodsand allowed it to be kept longer. This also likely led tastes in food to change back away from the subtropical foods that could have been grown in other parts of China (Figure 2).<ref>For more on food and technology related to climate, see: Chambers, F., & Ogle, M. (Eds.). (2002). <i>Climate change: critical concepts in the environment</i>. London ; New York: Routledge.</ref>