The Reagan administration in its anti-communism fight was helping countries that were against Communism and isolating countries that were pro-communists or had ties with communist States.
The administration took advantage of the huge doctrinal difference of the Sunni and Shia factions in Afghanistan to cause a political divide and alienate Afghanistan. This is an example of a classic "divide and conquer" scenario where two different factions are pitted against each other so they would grow weaker collectively and be easy to conquer.
The food sources of Native Americans of the North and Northwest differed from that of Natives that lived in the West and Southwest due to the impact of climate which determined the types of food that were available. People in the North and Northwest did not farm. Irrigation allowed the people in the west to farm in dry areas.
90% of the native americans were killed because they had never experienced the flew and thought they were powerful with the weapons they had Made from tree bark and other materials the forest came to have.
