I bought a good book (2nd hand) in Phnom Penh, Cambodia. It's a World Geography updated edition written by Thomas J Baerwald and Celeste Fraser. I bought this book because it describes certain nation in details mainly on its people, culture, and custom. Furnished with amazing pictures of villages all over the planet, it's a worth-buying one. Let me share you what this book tells about Indonesia (page 698): '' Uniting Indonesia has required great skill. Indonesia has over 230 million people living on islands spread over 4,800 km of ocean. Throughout its history, no one group of people has ever dominated the area long enough to give it cultural unity.''