What's the practical use of history? Well, it's mostly captured in Edmond Burke's
"Those who cannot remember the past are condemned to repeat it"
Those who do can often exploit it. In Guns, Germs, and Steel, Jared Diamond gives an example of a simple trap that Pizarro used to to help his tiny army defeat the millions strong Inca empire. His advantage, he claimed, was literacy, and his knowledge of the uses of the strategem from time immemorial - or rather from time memorialized in historical record. Without literacy, the Inca fell for the trap.
Most literate civilizations have practiced some sort of history, and the West imbibed the spirit of Greek and Roman history and has been diligent in it's practice.
The great exception is India. The oldest extant civilization has been singularly remiss in recording its own track through time. It's hard to believe that it hasn't sometimes paid Burke's penalty for that neglect. Almost all that we know about Indian history comes from foreigners, mostly invaders. Even today, it seems, Indians are slow to take to writing history. (via Arun)