As historical badasses go, they don't get much more badass than Genghis Khan. The Mongolian warlord's story is full of revenge, crazy adventures and enormously bloody battles. Hell, he was still commanding armies at the age of 72 (and this was in 1227, so that's like being 150 today, you know, after inflation) if you believe some of the records, anyway. We're talking about a badass for the ages.
Genghis Khan was born in Central Mongolia in the year 1162 CE under the name "Temujin", meaning "Iron Man" and you know that when your parents name you after a Black Sabbath song you're going to be trouble.
"The greatest joy for a man is to defeat his enemies, to drive them before him, to take from them all they possess, to see those they love in tears, to ride their horses, and to hold their wives and daughters in his arms."
— Attributed to Genghis Khan
"Heaven is weary of the luxury of China. I shall remain in the wilderness of the north. I shall return to simplicity and moderations once again. As for the clothes I wear and the food I eat, I shall have the same as cowherds and grooms and I shall treat my soldiers as brothers. In a hundred battles I have been at the forefront and within seven years I have performed a great work, for in six directions of space all things are subject to one ruler."
— Genghis Khan
"At Sarai, in the land of Tartary,
There dwelt a king who warred on Russia, he,
Whereby there died full many a doughty man.
This noble king was known as Cambinskan,
Who in his time was of so great renown
That there was nowhere in the wide world known
So excellent a lord in everything;
He lacked in naught belonging to a king.
As for the faith to which he had been born,
He kept its law to which he had been sworn;
And therewith he was hardy, rich, and wise,
And merciful and just in all men's eyes,
True to his word, benign and honourable,
And in his heart like any center stable;
Young, fresh, and strong, in warfare ambitious
As any bachelor knight of all his house.
Of handsome person, he was fortunate,
And kept always so well his royal state
That there was nowhere such another man.
This noble king, this Tartar Cambinskan"
Attack with aggression, but always have a plan of retreat.