Korriban

A Sith World. During the Dark Lords along with the Jedi Civil Wars. This world has the sole planet located in the Horuset System. It was used as a graveyard for Ancient Sith Lords and was later rebirth as a home and training ground for modern Sith. It was once a world of slavery of the Infinite Empire thousands of years before the first Sith Lords came.

Naga Sadow built his tomb millennia later around the Star Map, a artifact of the time when the Rakata had used the Star Forge. Carved into the sheer rock walls of these canyons are enormous tombs containing the dried, mummified remnants of the a range of Dark Lords of the Sith like Marka Ragnos, Naga Sadow, Ajuna Pall, and Ludo Kreesh as well as other great Dark Masters from various millennia.Korriban was occupied by the Sith race.

The Dark Jedi astonished the Sith with their teaching in the Force, and soon grand themselves to a God type, becoming the rulers (or considered themselves as "Lords of the Sith"). As the years passed, interbreeding occur between the human Dark Jedi and the Sith, until at final 2 people had become one. Korriban now as a graveyard for all the Sith who died throughout the wars, many artifacts are rumored to be in the Sith Academy.

Ossus

Ossus was once a teaching ground for the Jedi Order, and was the location of a vast museum of Jedi artifacts and ancient lore. Throughout the Great Sith War, Exar Kun caused a star in the close by Corn Cluster to go supernova, the quake from which would have awful effects on the planet. The Jedi rescue as various artifacts as they could, and had to leavr the rest behind.

The Neti Master Ood Bnar stood over a cache of lightsabers and twisted himself into his huge tree form, present the shockwave and protecting his charge for over four thousands years, until he awakened to fight perpetrator Sedriss during the reign of the reborn Emperor. It is understood that the Jedi Order was formed on Ossus.

Alderaan

Alderaan is a home planet in the space in Core Worlds. Within the story, it is the home of the fictional characters such as Princess Leia, Bail Organa and also, in 4000 BBY the Ulic Qel Droma who fought in the Great Sith War.

Distance from Core	5,000 light years
Region	Core Worlds
Sector	Alderaan Sector
System	Alderaan system
sun(s)	1
moon(s)	0
Diameter	12500 km
Length Of Year	364 standard days
Length of Day	24 standard hours rotation retrograde
Axial tilt	23°
Major species	Humans, Killiks (c. 1000 BBY)
Population	1.97 billion (before its destruction; 60,000 residents not on the planet at the time of its destruction)
Official language	Basic
Primary terrain	Mountains, Seas, Forests, Plains
Surface water	70%
Points of interest	Aldera (capital), Crevasse City, Castle Lands
Government	Constitutional Monarchy
Affiliation	Galactic Republic, Galactic Empire, Rebel Alliance

Here are the information of Alderann:

The Alderaanian people highly valued education, arts, architecture, poetry, the performing arts, and diplomacy. They placed high value in their participation in the Galactic (later Imperial) Senate. Though largely a democratic society, Alderaan was headed by a hereditary constitutional monarchy, under the historic Royal House of Antillies, and later through marriage the House of Organa presiding over the High Court and legislative High Council of Alderaan. Its monarchs have variously borne the King or Queen of Alderaan. The leader ofAlderaan from the end of Revenge of the Sith to A New Hope was Queen Breha Antilles-Organa.

Queen Breha was married to Bail Organa, who served a term as Senator during the events depicted in Revenge of the Sith, later serving as First Chairman and Viceroy of Alderaan. Traditionally, the heir of the Alderaan throne also serves in the legislative High Council of Alderaan and a term as Senator of Alderaan. Queen Breha and Bail's heir and (secretly adopted) daughter was Princess Leia who was serving as Senator of Alderaan in the Imperial Senate during the events depicted in A New Hope.

As you may know, the planet's history was wiped out by Death Star in Episode IV: A New Hope by the hands of Darth Sidious.