This chapter investigates historical climate change and its impact on human activities, particularly agriculture. Climate is analyzed as a long-term atmospheric system shaped by Earth’s natural dynamics, celestial interactions, and, more recently, human activities. The discussion traces climate history from geological times to the present, with a focus on temperature and humidity variations since the early Holocene. It highlights critical climatic thresholds, such as the Holocene Megathermal approximately 3,000 years ago, followed by a gradual cooling trend. The lecture examines temperature fluctuations across historical periods, noting scholarly consensus on key climatic events, including the Medieval Warm Period and the Little Ice Age during the Ming and Qing dynasties. It also explores regional humidity shifts in eastern and western China, as well as the role of extreme climatic events. The lecture concludes by demonstrating how historical climate changes influenced natural vegetation patterns and shaped key agricultural boundaries, such as the southern rice–wheat rotation zone and the northern wheat cultivationWheat cultivation limit, illustrating the deep interconnections between climate, vegetation, and agriculture.