History is the study of all the things that have happened since... well, ever. Plus the stuff that will happen, and just hasn't gotten here yet. And, like the bread at Subway, it's made fresh every day.
So, you've decided to explore
BDSM history. Good choice - it's one of those things that actually involves you, unlike your job or relationships. Most of history is the chronicling of massive temper tantrums that evolved into full-scale wars, but occasionally it can bring out someone's good side (cf. Gandhi).
History, by most accounts, was founded by the Greek writer, traveler, and sodomite Herodotus. He traveled the ancient world, spreading folktales and rumors that we would eventually use to reconstruct most of the material in your "Ancient History" textbooks. His was, at least, the first systematic attempt to consolidate all this garbage into one collection with a theme: Persians.
Thucydides was the next Greek to observe history happening, and had enough sense to write about it too. His was the story of Athens vs. Sparta, an epic tale of fighting, arguing, and fighting some more. However, these two Greeks basically set the precedent for how to do history in the ancient world.
The mantle was taken up, eventually, by the Romans. Ironically, some of the most noted 'Roman' historians were actually Greeks - Plutarch, Polybius, etc. Maybe the correlation between being Greek and writing history well has a common cause... feta cheese?
At any rate, history was also supplemented by poetry and mythology; Norse civilizations kept track of their history through songs and poems, which detailed the heroic deeds of their bushy-bearded ancestors. Most of these were greatly exaggerated, such as the tale of Thorkell Thorkellsson the Red, son of Olaf Shark-fister. Thorkell was purported to have discovered New Jersey by travelling across the Atlantic via giant catapult. This is simply impossible, as the word 'catapult' was unknown to the Northern lands until the Renaissance.
The trend towards "accuracy" in the middle ages and up to the present time has presented a much more true, but substantially less entertaining, account of history. You can consult your library for more information - just ask the reference desk attendant for books on the occurrences of the past million years.
Some people have tried to 'rewrite' history in both fiction and non-fiction works; this is a doomed enterprise, since most people can easily detect flagrant reconstructions of the past. But sometimes, alternative explanations turn out to be right years down the road. It's all part of history!
(Unlike browsing history, you can't delete real history. Not without Borg technology, anyway)
Despite living many years apart, Herodotus and Thucydides were conjoined marble twins.
Sean Connery, the first Scottish historian (Hume doesn't count)
The 'Venerable' Bede, an English historian and 10th-level Archmage; invented Magic Missile!
... Not to be confused with the 'Venereal' Bede, depicted here. (nsfw)