Purpose of learning history

Why do we read history in school? What is the advantage of learning our past? What benefit do we get by learning what our forefathers did many hundred centuries back?

I feel the purpose of learning history is about knowing our base, knowing our roots. Another purpose of learning history is to learn from experience and not to commit the same mistakes someone did some years back.

But interestingly, history involves some politics too. History is written in such a way so as not to cause displeasure to the rulers. Sometime same history is written and told in different way to two different audiences.  (I know the same history is presented in different way in India and Pakistan!)

History usually tells us about lots of bad things also that happened in past - wars, massacres, loot, exploitation, rape etc. Many hundred years back, people were not so civilized. There were blood-thirsty kings who always wanted to expand their kingdoms. Some people were aggressors and some people were victims. In twenty first century when we read bloody history that my ancestors were attacked by their ancestors, should we seek revenge for those misdeeds committed many hundred years back and attack their descendant now? If we follow the principle of revenge, then India should now attack England because the English men came here in 1601 to do business but then colonized and looted my country for three hundred years. Or, whole of Asia should attack Mongolia because Genghis Khan created lot of terrors here. No normal person would ever think to do these. We can't undo what has happened in history. We shouldn't try to take revenge for something that happened in past. What has happened in history has happened. We should learn from it rather than seeking to undo events in history.

But the most important question is: should we seek judicial intervention now for some of the misdeeds of history? Will the judiciary be able to resolve it? I wonder!