Earth in Two Clusters is considered "home to all mankind spiritually". However, the reality differs from the ideology.
The Bau was so dominant on Earth for more than 5,000 years that the clan considered the planet theirs and, therefore, enfored harsh entry fee when foreginers would enter the planet. Furthermore, background screen had to be done. In the end, for almost all people who lived elsewhere, visiting Earth was a distant, if not impossible, dream.
As of year 9599, Earth's popluation is just 1 billion; The Bau expelled 5 billion to Moon.
Earth is the political center of United Sol and the Ark in Washington DC is the heart of the federation.
The Bau had complete control over the Earth. The only exception was a small city-size zone deidcated to the Ark called Washington DC.
The land was divided into nation-size divisons. For an example, Germany still existed under Division Ger. England existed under Division Eng. However, concept of ancient nations were long lost and everyone on Earth was simply referred as Earthians.
The Bau appointed administrators for each divisions.
One of few positives under the Bau's rule was that Earth regained its lustful green forests due to reducing human presence to just 1 billion population.
Earth was the heart of United Solar system federation.
United Sol was founded in 7192. The official name was "United Solar system Federation". However, as generations passed, the title was shortened and people simply referred it "United Sol". However, the full title was still the official name found on documents.
Originally, back in 7192, president of each planets, Venus, Earth, Moon, Mars, and Saturn went through an extensive election to choose a winner by popular vote. The winner would be the president of United Solar system Federation. However, being the president of USF meant little to none at that time.
Later, the system was changed. Whoever won the election would become the president of Earth as well as becoming the president of USF. Furthermore, Moon had lost its political system and went under direct control of Earth and Jupiter outpost was built and went under control of the president of USF, giving more powers to the president.
Presidency period differed from each president. A president was entitled to hold his (There had never been a female president.) position until he'd lose more than 70% of support from political factions of the Ark at the house level. Until the fall of United Sol, no president was ever forced to resign. Rather, they died of age or was assassinated or was killed in action.
Gawain Klisis (7006 - 7798) was the 3rd president of USF. This was also when USF was starting to be called United Sol. Gawain brought a golden era for United Sol. He expanded mankind further outside of Solar system and started to construct colonies outside of Solar system. He had also made series of plans to reach Andromeda cluster. Unfortunately, however, he died of age before he could see the end of the epic project.
Mirren ( - 9599) won the presidency of United Sol on 8803 and became 6th president of United Sol. He was personally a close friend of Cecil Klisis and chose Cecil to be his first adviser.
Previous presidents did not bother with Gawain's plans to reach and colonize Andromeda cluster, but Mirren took the project and continued it. Some said that it was Cecil' request to take on his grandfather's unfinished quest.
However, it was never confirmed. Full colonization of Andromeda cluster was successful. All was well until Mirren started to change. He imposed large tax on distant inhabitants in Andromeda system and a mishap of calling the immigrants "Poor and low" caused much stir.
Continued unreasonable tax and unfair treatments pushed Andromeda immigrants to edge, and inhabitants of Andromeda system revolted. Mirren attempted to sort out the rebellion by assigning Cecil Klisis as a commander of a large fleet, but Cecil refused and quit. The rebellion was successful, and Andromeda system declared independence. This was the birth of Andromeda Republic which would later become Andromeda Union.
Mirren was assassinated while in his private space vessel near Venus on 9599. Why he was there and how he was assassinated remained unknown. Its blackbox was collected but provided no significant clues. Cecil Klisis was immediately suspected but lacked any kind of evidence to even warrant a formal search.
7th president of United Sol was Gvew (9001 ~ 9613) was just a chief security guard at the Ark. He abused "grace period" and launched full assault on his opposing factions. Gvew had two children, a son (Reed) and a daughter (Devon). Hating his father's deeds, Reed left Sol system and worked for Aedy Freedom (Freedom colony), but Devon remained with her father until 9613 when her father was assassinated during "Milk way to our home" tragedy.
8th president was the last president of United Sol. His name was Fraser Bau (9411 ~ 9670). He was formally a son of a wealthy merchant on Moon. He attempted to heal deeply wounded economy of United Sol with his adviser, Len. His efforts never really paid off, and he could not stop rapidly declining United Sol. On year 9670, Cecil delcared a war on United Sol and Earth defense fleet lost the first battle so badly that the fleet was literally wiped out. Earth was bombarded shortly later, ending United Sol.
Earth bombardment by Cecil destroyed most of infrastructures on the planet. After Jupiter administrator Emuel took over the planet, he invested none on the planet to make any proper recovery. This was due to Emuel having no sentiment over Earth.
Therefore, Earth remained to be fairly primitive afterwards which Moon residents were pleased about.
Milky way to our home tradedy had little impact on how Bau continued to behave. However, on the whole, it had a profund negative impact on United Sol.
Gvew's decision to shoot down the refugees was enough to get him assassinated which allowed to let the Bau have control over presidency, and from there, United Sol went downhill repaidly.
For the record, Fraser Bau had agenda of his own and attempted to recover but none of his efforts were effective.
A group of six planets were called "Smuggler's Den" in Andromeda cluster.
A-2541a, A-2541b, A-2541c, A-2541d, Jupiter II, and Freebie in the region were called "Smuggler's Den". The number, 2541, meant the year the planets were discovered. Freebie and Jupiter II were given unique names meanwhile. All planets in Smuggler's Den region were barren planet and naturally incapable of holding any life on its own.
Therefore, domes were created to hold life artificially on the cheap.
Freebie was a trade hub and was the capital planet in the region. Even so, the planet was very poor and presented one of the worst living conditions.
Because of a well-known fact that everyone living in the region was so poor, and that people began to treat them differently as if they were slaves and lower beings, this had caused for a strange religion to raise.
This cult spread widely to entire Smuggler's Den at speed of light, and majority of population, over 95%, in the region recklessly joined the cult. On 9612, the cult rose and ordered its believers to head to Earth to receive "true blessing".
600 million perished in the end along with 7th President of United Sol.
The whole story on this tragedy is well covered and have its own arc: Milky way arc.