Indus Valley Civilization
Known to historians as one of the largest and earliest civilizations to not only colonize a continent but thrive in it, the Indus Valley Civilization was extremely advanced. They were known to have practiced dentistry, mathematics, and even had pioneered the first urban sanitation systems. By 1500 B.C.E. the civilization had completely vanished- and historians are not quite sure why. One theory suggests that they were forced to pack everything up and leave due to extreme climate changes and a fall in agriculture.