Typically do civilizations which traded with each other have written records of each other? I am wondering if the language, people, rise and fall of society in Indus Valley Civilization is accounted in other civilizations lending to the credence of Aryan invasion theory of Dravidians. Why is it difficult to prove or disprove the hypothesis? General answer and Aryan invasion theory as example. Writing began in 3500 BC before the final of Indus Valley Civilization and trade should be existing i...
