Without the foundation, you can not build your walls, or put on a roof. According to some, the goal of history is to explain how, or why the facts came to be, to demonstrate the meaning of the facts. When you write papers in history, you must present the facts along with your generalizations and observations. Failure to do so may confuse the reader as to what is meant, or bring about conclusions contrary to actual facts. This is a common problem with beginning students in history.
Evidence is a way of engaging facts.
Evidence can be documents, statistics, eye-witness accounts, professional analytical studies, controlled experiments.