In the current era, historians and laypeople most commonly use the term Second Federation. At the time of its existence, though officially named the Federation of Sol and Affiliated Systems, the Second Federation was often called the New Federation or SolFed to distinguish it from its predecessor, the Federation of Sophonts (First Federation) and what became the Terragen Federation based on New Earth.
After the collapse of the First Federation in 2099 AT, a series of relatively short-lived interim governments took power in Solsys in order to provide basic coordination and security. This interregnum was far from a period of anarchy, with most governance provided by the former First Federation's member states. These interim governments took a variety of shapes from the modo-centric Solsys Alliance to the benign neglect of the transapient-led Protectorate of Sol. However, each of them failed to thrive as infighting between the Solsys polities and the ruling transapients eventually led to their downfall.
In 2531 AT, representatives of five second singularity transapients, Prince of Order, Augusto, A Blessing to the People, Reflections on the Law, and Ascendant Villager (AKA Abule Giga) met at Kronia Complex in orbit around Saturn. Dissatisfied with the state of affairs, the five transapients, thereafter known as the Pentarchy, established the Federation of Sol and Affiliated Systems. While they retained many of the trappings of the old First Federation, the Federation of Sol and Affiliated Systems was in practice very different. Though, many of the former First Federation member states, such as the Republic of Mars and the Plutonian Confederacy continued on and had domestic autonomy, modosophonts took a much smaller role in system governance. During the Second Federation, the Pentarchy handled almost all trans and intersystem issues with little input from the sub-polities though there was limited representation in the legislature and other deliberative bodies. There were a number of other first and second singularity transapients active in Solsys at this time. Though not members of the Pentarchy, they often oversaw or helped administer individual sub-polities. Naturally, many transapients remained independent and interacted little with the Second Federation's modosphont inhabitants. Ascension attempts to reach the third singularity occurred periodically but invariably failed. However, these did lead to a proliferation of S1 and S2s, many choosing to reside inside the Veil on Saturn.
The Federation of Sol and Affiliated Systems operated and evolved for centuries as its member states prospered. In and around Jupiter, the cyber-democratic Conclave of Storms united most of the Jovian nations. Neptunians embraced a rel-focused culture in their whimsically named Republic of the Clouds. However, Solsys was not without its problems during this period. On Mercury in 2650 AT, a nanoecology accident led to an infestation. The Second Federation began a long and costly clean-up effort. The Second Federation had a complicated relationship with the megacorps operating during this time. Although several megacorps maintained branches in Solsys, the Second Federation enforced regulation with varying degrees of success.
Outside of Solsys, the Federation of Sol and Affiliated Systems initially inherited a number of sister systems, colonies, and outposts from its predecessor. Though the Second Federation had access to the nascent Wormhole Nexus through Einstein's Gate, it was of little use to reach most of these systems. This forced a heavy reliance on the Lightways, the Beamrider Network, and conversion drive starships. As time went on however these wayward territories invariable broke away or fell to a rival power. By the 3500s, the Second Federation held sway only in Solsys, Sirius A and B, and a handful of nearby minor systems.
In 3726 AT the Federation of Sol and Affiliated Systems abruptly collapsed. The transapients of the Pentarchy, the guiding lights of the Second Federation since its inception, peacefully dissolved their ties with each other and announced that a new provisional government would take over by the end of the decade. It has been theorized that some form of agreement between the Terragen Federation's Yave and GAIA bought about the Second Federation's disintegration, though opinions differ. A Blessing of the People and Ascendant Villager left for the emerging sepheriotics. Reflections on the Law withdrew to a computronium node in Callisto and restyled eirself the Game Master, becoming increasingly enigmatic and reclusive. A Prince of Order and Augusto remained in Solsys and stayed active in administration. The now defunct Second Federation's member states largely remained intact. Soon after the Second Federation's collapse, the Solsys Organization came to power and remains the system wide government to this day.
Similar to its predecessor, the Second Federation was too diverse to have a single unified culture. New technologies radically changed modosophont life compared to that in the old First Federation. Though conditions varied based on location, generally speaking the Second Federation enjoyed, at least for the time, a high standard of living with true post-scarcity economies being the norm. With the widespread use of engenerator technology, modosophonts increasingly kept active backups in case of attacks or accidents, as angel networks were not yet available. Vots were widely employed and acquired through government-funding vot libraries. This further reduced the need for modosophont participation in the economy allowing more people to devote themselves to culture, arts, and personal endeavors. Old Anglish remained the lingua franca though shifts towards Middle Anglish were becoming apparent. Religiously the Federation of Sol and Affiliated Systems was diverse, with adherents of nearly every faith and philosophy. Over the years, new creeds such as Keterism and Solarism gained footholds in Solsys.
Although it lasted slightly longer than the First Federation, the Federation of Sol and Affiliated Systems never rivaled the influence of its larger and far better-known predecessor. It did however provide a millennium of stability in what was still an important system in the inner sphere. Memetic vestiges of the Second Federation continue into the current era. Secundus Foederatio Aeterna is a large virch in the Jinvanco system based on the Second Federation. In the middle regions, an S4 named Pentarch claims descent from at least some of the Second Federation transapients though this has not been independently verified.