Remember that one time?

So I had an interesting experience yesterday. I was actually sort of expecting it, and knew that it would occur at any time, just didn't know when. Generally speaking it was neither a positive nor negative experience, instead a catalyst for thought.
My 11th graders have been studying speeches these past couple of weeks. We had been looking specifically at American Revolutionary speeches, ie Patrick Henry, Benjamin Franklin, and Thomas Jefferson. Yesterday however, I decided to bring in an example of a modern day speech. I chose the speech Elie Wiesel gave last year at the site of the Buchenwald Concentration Camp on the anniversary of D-Day. President Obama was in the audience (having just come from Cairo where he gave his famous Cairo speech) as well as Chancellor Merkel. The speech is beautiful and I do recommend giving the transcript a look. Wiesel talked about the feeling of optimism people had for the world after the end of WWII. Maybe after such horror and devastation, the world would have learned its lesson that "all wars are absurd" and that peace would reign. But the world hadn't learned he argued. Instead, destruction and war became the stories of decades upon decades. He hoped however, that today with new leaders promising 20/20 moral vision, the world would finally seize the opportunity to leave war, hatred, and dominance aside and finally learn the lesson that history has so vehemently tried to teach; that peace and understanding of others is both possible and imperative here on Earth.
The students liked the message, only its impact was somewhat lost for one particular reason. They didn't know what a Concentration Camp was. How can you understand the plight of peace and the paradoxical optimism Wiesel felt after his liberation if you had never been introduced to the original suffering? Now, having to explain to a group of Egyptian students what a Concentration Camp is without discussing religion or politics (school rules) is a verbal feat of acrobatics. My sentence went something like, "It's where they took the Jews and other people during WWII."
This incident sparked a discussion in the staff room, not so much about the Holocaust, but about history in general. Is there such thing as a common world history? Or even a commonly acknowledged history? Should the African continent study the same history as the North American one? More importantly, if history becomes regionally or perhaps even politically motivated, will we ever really understand each other?