Herodotus described the Thracians (who inhabited what is now roughly modern Bulgaria, Romania, the European part of Turkey and northern Greece) as the most numerous nation of all - apart from the Indians - and said that they would be the most powerful of all nations if they didn't enjoy fighting each other so much. There may have been a million Thracians, divided among as many as 40 tribes. Ancient writers were hard put to decide which of the...