Xanthippe does not interfere in human politics at all, not even when it becomes open warfare. Only real threats to the Tree are countered, and these are extremely rare.
The main issues in human politics are handling access to the timeline, what to do with new human arrivals and what policies to pursue in the Consensus virtuality. It is generally believed that the other cultures of Ex will not accept the current chaotic mess of human politics, where different groups have different policies and travel to the timeline with little coordination with the Schedule. Hence many groups work hard to create a unified human front; not necessarily a political unification of all humans but at least a unified human front towards the rest of Ex. Struggling against this are many groups seeking to retain their independence or not acknowledging any other power at all.
The current situation is dominated by the "Nova Roma Consensus". The NRC is largely a compromise between the major cultures, and has de facto most political, technological and coercive clout to bring about much of its policies.
The NRC handles new arrivals through the Arrival Committee. The Committee consists of representatives (mostly diplomats, contact specialists or chrono-anthropologists) of the main powers, and waits in or near the bays for new arrivals. They meet the often disoriented arrivals, perform a brief greeting/debriefing (with extensive support through their wearables with a large panel of experts), give them a nanovaccination and bring the arrivals into Namaqua.
To help the arrivals deal with the complex situation a "public defender" is selected. The defender is a legal advisor intended to safeguard their rights and help them fit in with the Ex administration. The current system involved the Committee selecting a suitable defender and then allowing the defender to bring the arrivals to their home habitat. The selection process is a typical Aquincorian bidding system: the different groups bid for the right to decide the defender, with part of the payment going to a fund for the arrivals and the rest to funding the Committee.
The issue of control over timeline access is problematic. The NRC agreements limit phasing equipment to the bays, and demand that jumps to the timestream be cleared with the Timeline Access Board (TAB) which then clears it with the Consensus. This holds most of the time, and limits access to approved operations (in Aquincorum access is approved by a senate committee, in Magellanica by the Captain). Access to the bays is also discreetly controlled by the TAB. However, Shoukakegawa and several disparates do not agree with the dictates of the TAG and travel according to their wishes.
Before the NRC the situation was far more anarchic and dominated by how the Lamplandae "clans" handled things. One leftover from this period is the restitution system of inter-cultural law. When somebody has been wronged, they can claim restitution from the perpetrator. This is overseen by a judge, selected by both parts, who decides on the guilt of the involved and the size of restitution. The NRC is doing its best to become the only judge of restitution, but in the labyrinth and many Lamplandae settlements wandering lawbeings are the rule. Especially the Taiuatta have enthusiastically taken on the role of judges, as it gives them excellent chance to see human barbarism. A similar system appears to be used among mainliner cultures, where entire cultures sometime act as judges.
The most important nation, not so much a successor of Rome as a linguistic construction and political expediency. The first human arrivals at Ex were fairly small groups utterly different from each other. The Karnten people were introduced by the Nao and Xanthippe, the Lamplandae were a big group of disparates with a somewhat related history and the N'Modugno a post-singularity culture; none had much to offer to each other. Other arrivals attempted to set up some form of pan-human association but failed at it.
Then the Republica Aquincorum migrated to Ex Tempore, soon after the N'Modugno had made early interference in human history (that landed them in serious trouble with the other cultures). The Republica was a technologically advanced, unified and had ambitious plans. They arrived with a small city-timeship. During the pause in temporal exploration caused by the N'Modugno the republic settled in and began dealing with all other humans and other accessible cultures. The republic diplomats were fairly successful, and the inflow of further Latinate people during the following period of cautious post-Aquincorum exploration strengthened their position. As Latin was a language reasonably well documented in many post-Roman timelines it also helped as a lingua franca for many new arrivals.
The introduction of the republic was not taken kindly in some quarters, and when the Shoukakegawa arrived the conflicts escalated. The Shoukakegawa came from a history where the west never got anywhere and mankind instead branched out in a multitude of sea- and space-based clades; they were naturally far more interested in exploring (together with their Ekichou allies) this subset of possibilities rather than anything that had to do with worlds where the Roman Empire had had an impact. Using devices they got from Ishdubar, they attempted a coup. The ensuing war practically crushed both sides.
However, the Ishdubar advantage proved fickle and the inter-clan coordination too weak to stand against the might of the other groups. When Strigae and Trilo trade interests sided with the Aquincorians the Shoukakegawa clans decided it was better to honorably end the fighting rather than see a war destroy them. A peace accord was eventually reached and both sides turned to repairing the damage.
A new organization for interultural interaction was set up, Nova Roma Consensus. The name was a clear hint at the strength of the Aquincorians and their ambitions. NRC was intended as a kind of combined trade alliance and United Nations aiming for an unified voice of the humans in Ex. At first merely an organization, it has grown into a de facto nation despite its internal divisions.
NRC has a complex organization, with different branches regulating different human (and nonhuman) activities. A central portion is the Curia, holding representatives from the human settlements with votes weighted according to population, wealth and indices of networked political importance. The Curia is formally the body that deals with the Council and oversees the committees dealing with the timeline.
Currently the Republica is growing fast, although the loss of the Utopist Movement into the timestream has hampered them to some extent. They are dominating the NRC, but some Aquincorians worry about the new arrivals who might tip the balance to new political constellations.
NRC currently consists of Conventus Lamplandae (represents the Lamplandae and N'Modugno through the Fygkjha), Republica Aquincorum, UJKH, Shoukakegawa, Nitlaki and Belkazanthe.
Magellanica and the Third British Empire are currently observers. The Empire has petitioned for membership status. Bia Map represents the virtual nations, and there is a group of mainline observers and avatars of Xanthippe.