Causes: environment, economics, political. Effects: clashes between people, new technology, redistribution of population, blending languages, quality of life improved, resources, jobs, food become scarce. Strongest cause environmental. Stronger people move in on another people and then lesser people move because of the stronger people coming in. Push= famine, war, disease (negative). Pull= farmland, rivers, religious tolerance (positive). Shapes new languages, spreads ideas, new clothing, etc. (cultural blending examples) Some achievements include minting coins, writing system, built stone structures, etc. Aksum was rich in natural resources like salt, rhino horns, ivory, gold etc. but was less rich in human made resources like cloth, glass, and wine. Aksum traded with other peoples for the materials they wanted. To adapt to their mountainous location after the Muslims invade they used terrace farming, made dams, made canals, and cisterns to help with the environment they lived in.