Nearly 40,000 BBY, individuals who contain a certain sensitivity to the Force are gathered together from around the galaxy and taken to the planet Tython. Upon arrival, Tython is covered in a powerful Force Storm, a conflagaration of Force energies manifesting in the form of extreme weather patterns, volcanic, and/or seismic activity. Upon landing, the Force sensitive individuals began studying the ways to control and use the Force. It was during this time that they learned that the Force storms were caused by a large unbalance in the Force and that Tython was exceptionally sensitive to those Force storms. It was for this reason that they began studying a balance between the light and the dark sides of the Force, forming an order called the Je'daii Order, a name that means "Mystic Center" in the native language of Dai Bendu, one of the species brought to Tython.^[1]

Approximately 15,000 years later, the Galactic Republic was founded, and shortly afterwards, the members of the the Je'daii order, now by this time the familiar Jedi Order, became the protectors of this new Republic. During this time, the teachings of the Je'daii, which taught a balance with the force, started to become polarized and the tenets of the Jedi Code began to take hold. As members of the Jedi order fell to the Dark Side of the Force, they were expelled from the Jedi order.

There is no emotion, there is peace.
There is no ignorance, there is knowledge.
There is no passion, there is serenity.
There is no chaos, there is harmony.
There is no death, there is the Force.

The Jedi order, soon after joining the Galactic Republic as its protectors, began developing a code that all future generations should adhere to. This code has helped guide many generations of Jedi, and helped them to maintain a level of decorum necessary to act as arbiters and negotiators. It is also this code that helps the Jedi remain cool during battle and maintain a level head, even when combat is at it's worst. It is from this rigid code, however, that many Jedi began to fall to the Dark Side.

The Jedi Order, while primarily a defensive and exploratory arm of the Republic, still needed a way for its members to protect themselves and to uphold Republic Law on planets that they might travel to. This lead to the development of seven forms of lightsaber combat. When the Republic fell approximately 32 BBY, it was believed that all knowledge of the forms had been lost as well. Fortunately, a copy of the Jedi Path^[2] survived and was discovered by Luke Skywalker. Inside the pages, among other great teachings, included the seven lightsaber combat forms. They are:

1. Form I: The primary form taught to all padawans at the academy.
2. Form II: Makashi - a well-balanced form, designed for lighsaber-to-lightsaber combat.
3. Form III: Soresu - A purely defensive form, ideal for situations where you are ambushed or wish to wear your opponent down.
4. Form IV: Ataru - A highly aggressive form, containing lots of acrobatic maneuvers. Care must be taken to end the fight quickly or risk wearing yourself out.
5. Form V: Shien/Djem So - Another balanced style, Form V is composed of two different styles. Shien Do is primarily suited to ranged opponents, while Djem So is ideally suited to lighsaber-to-lightsaber combat.
6. Form VI: Niman - The most balanced of all forms. While it has no particular strengths on its own against other Force users, this form is ideal for the Jedi who does not engage in combat often.
7. Form VII: Juyo - A purely offensive form. Many Jedi shy away from this form due to the form's design for direct attack with no regard for defense. To counter this form's lack of defensive maneuvers, this form relies on the Jedi's speed to help him dodge attacks.

The Galactic Republic and Sith Empire, for centuries, lived isolated from each other and forgot about each other. When two Republic hyperpace explorers, individuals who dare the unknown to find new hyperpace routes to travel, stumbled upon Korriban. After the two intrepid explorers were caught and brought before the Sith Empire, certain Dark Lords within the Sith Empire began dreaming of new lands to conquer. Using guile and subterfuge, Dark Lord Naga Sadow was able to rally the Empire into an invasion against the Galactic Republic. The Jedi Order was eventually able to turn the tide against the Sith Empire and give the advantage to the Republic Fleet.

The Sith Empire suffered heavy losses during the war, but were not eliminated. Some Sith survived on other worlds, and were able to maintain the Sith tradition there. The Emporer, himself, pulled his forces back into the Unknown Regions to rebuild and bide his time until he could strike back again at the Republic

More than a millenia after their defeat in the Great Hyperspace War, the Sith Empire, restrengthened, launched an all-out attack on the Republic in 3681BBY. This war lasted 28 years, attacking major Republic strongholds such as Corellia and Alderaan. While the Republic and the Sith Empire both had their share of major victories, many battles resulted in stalemates where both sides pushed against each other with little ground gained. As the war entered it's third decade, the Jedi saw that the war could not be won and recommended brokering a peace. The Sith, given to their natual tendencies of aggression, used this time to lay seige to Coruscant, the capital planet for the Republic, destroy the Jedi temple, and execute the Supreme Chancellor. Yielding to certain concessions within the Treaty of Coruscant, the Republic was forced to give up control of many out-lying systems to the Sith Empire. The Sith, no longer thirsting for conquest, removed themselves back to their Empire in the outer rim systems. The Jedi, blamed for the Republic's defeat, and suffering from heavy losses during the 28 years of conflict, retreated to the ancient home planet of Tython to commune with the Force, refocus themselves, and rebuild the Order. Tensions between the Republic and Sith Empire remained high for years to come, especially among border systems, resulting in a prolonged Cold War and numerous border skirmishes. After 12 years of a tumultuous peace, if it could be called such, the galaxy saw the war re-ignite.

^[3]

Darth Bane and his apprentice Zannah

1000 BBY saw the fall of the Sith. At the Battle of Ruusan, the Sith, held together by a fragile alliance of a common enemy, were finally defeated by the Jedi.

Or so it was believed.

There was one survivor of the Battle of Ruusan, a Sith who called himself Darth Bane. After witnessing the destruction caused by the constant in-fighting of the Sith, Darth Bane instituted the Rule of Two, a rule that would guide all future generations of Sith Lords.

The Rule of Two was meant to keep the Sith tradition alive, while eliminating the in-fighting and keeping the numbers small enough to stay hidden from the Jedi Order until the time was right to exact their revenge.

Two there should be; no more, no less. One to embody power, the other to crave it." - Darth Bane^[4]
(Karpyshyn, D. (2007). Star Wars: Darth Bane - Rule of Two. New York, NY: Del Rey Books)