This thesis focused on the historical investigation of environmental changes in Simada wäräda during the twentieth century. Environmental changes seriously affected people of different qäbälé’s in the district. This thesis examines the action of human beings as well as animals on the surrounding environment and vice versa within the twentieth century in the district. The thesis also examines the effects of environmental degradation in Simada and the conservation measures of the two successive governments, the Därg (Military) and EPRDF (current), to reverse the problem. To this end, the researcher collected and explored both primary and secondary sources. Former Sämén and Bägémdir Governorate General Archival Center and National archives and library agency, followed by Simada wäräda Agriculture and Rural Development Office and Simada wäräda Culture and Tourism Office are the main sources to accomplish this thesis. South Gondär Administrative Zone Agriculture and Tourism Office are additional sources for the researcher. The researcher also conducted interview with selected and aged persons. Furthermore, GIS analysis used to show land use and land cover changes for twenty years of district. This thesis described the interaction of human beings with the environment, the change in the environment and its influence on the lives of the people. The results showed that changes in the environment chiefly happened during the Imperial regime and the socialist military government of Ethiopia. Population pressure, increasing demand for agricultural and grazing land, and for wood for fuel and construction are the primary causes for environmental degradation of Simada wäräda. As a result the wäräda is deforested, the soil depleted and land degraded through erosion. This environmental crisis frequently affected the life of human beings as well as animals in Simada and neighboring wäräda‟s. The major consequences of environmental alterations in the wäräda were temperature change, the decrease of natural forests, and reduction of vegetation, the repeated occurrence of disease and pests, water shortage, drought, famine, flood and others. All had resulted in death of many people and