After many battles over thousands of years, only two Sith remained. Darth Bane, Sith Lord and his apprentice, Darth Seer. The fled to Coruscant and stayed hidden. Bane was the first to establish the "Rule of Two". Only two Sith would rule at one time. A Sith Lord and A Sith Apprentice. After Darth Baned died of old age, Darth Seer took on the title of Sith Lord. After doing so he recruited a new apprentice, Darth Mongerer. It was then that Darth Seer made the word "Darth" which meant "shadow warrior" equal to the word "Lord", in honor of Bane. Lord Mongerer was eventually confronted and defeated by a Jedi. However, Mongerer did not let this Jedi know that he was a Sith. His Apprentice would assume the role of Sith Lord.
Two centuries into the secret Sith occupation of Coruscant came the Sith Master, Darth Gilgon . Gilgon took on an apprenctice named Augor. After the Death of Lord Gilgon, Darth Augor would go on to become one of the most powerful Sith masters of all time. After slaying dozens of Jedi, He was ambushed by 17 Jedi. Among them was the well Jedi, Yoda, who at the time was only between 150-200 years old.
Over the next few centuries New sith Lords came and went. Norius Havok, Darth Frordon, Baltimort, and Imperius were the last few Sith Lords Before the Clone Wars. After Imperius killed his master, Lord Baltimort, he found his apprectice on the planet of Naboo. A young boy named Dantius Palpatine. Imperius named his new apprentice Darth Sidious. As Sidious got old, he also got stronger. He finally killed his master by cutting off this arms then finishing him by slicing him in half, from head to feet. Darth Sidious later took his old Name Palpatine and established himself in the Galactic Senate. Over the period of many years, he took on several apprectices, one of which broke the "Rule of Two" and took on his own apprectice/s. Sidious found out and slew his apprence and his students. He then took on a new Zabrak appretice whom he named Darth Maul. Maul is well known for his double bladed light saber and for killing Jedi Master Qui-Gon Jinn in a battle nic-named "Duel of Fates". After Slaying Qui-Gon Jinn, he himslef was killed by Obi-Wan Kenobi, Jinn's Padawan. Finally Sidious found his final apprentice; a young Jedi named Anakin Skywalker. Sidious tutored Anakin in private and eventually turned him to the dark side. Anakin comes to be Darth Vader.