A long chain of under water volcanoes are called Seamounts.
The Mongols set up a tribute empire called The Golden Horde. Serfdom arose as peasants gave up their lands to the aristocracy in exchange for protection from the Mongols. Moscow benefited financially by acting as a tribute collector for the Mongols. Mongol rule kept Russia culturally isolated from Western European trends such as the Renaissance.
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Climate patters - people migrate to temperate regions
Traditions - people migrate to areas where famous things happened
Elevations - most people don't live in the mountains
Ethnicity, Religion, Language - people of the same ethnicity, religion, and/or language will stay together