Recorded history is defined by written language, hence the phrase recorded history. The first written language is the Sumerian language. It developed around 3300 BC in Sumeria in southern Mesopotamia. So to answer your question, recorded history is about 5000 years old.

http://www.ancientscripts.com/sumerian.html http://www.omniglot.com/writing/sumerian.htm http://etcsl.orinst.ox.ac.uk/edition2/language.php