Twin Union

The Twin Union was a political alliance between the Exarchs of Selucenia and Lucrenia, which was forged during the early years of Thaerseimai. The alliance was born out of necessity, the two provinces uniting to defend their southern territories from invasion by the Exarch of Yethisia.
The two southern Exarchies have always maintained close relationships, in part due to simple proximity. Governed from the twin cities of Selucia and Lucria which are separated by just 125km, the two provinces have always enjoyed strong trade links: commonly Lucrenian iron for Selucian stone. Borders between the two provinces remain open, and as a result natives from both Lucrenia and Volodaria can be found across the south.
Thaerseimai began in 391 IF, with Sundemar's conquest of the Nara peninsula, and plunged the Empire of Nara Tok into chaos. The Senate stuttered and ground to a halt as the Great Houses of the northern Heartlands descended into petty feuds. As a result, the two southern provinces were almost entirely cut off from the north, relying on the Exarch of Yethisia for easy access to the rich northern markets. The Yethisian Exarch was quick to exploit this situation by greatly increasing tariffs on goods from the south. The southern Exarchs were angered by this attempt, and decided that they would not kowtow to the Yethisian demands. They began to send their caravans along old smuggler's routes, avoiding the Yethisian checkpoints.
An uneasy status quo persisted for a few years. The Yethisians expanded their border patrols, searching for the illegal caravans and seizing their goods as contraband, while southern traders attempted to evade capture until they could reach the city of Harinia , which remained mostly outside of the Exarch's control. Trade on the Grand Lumber Road ground to a standstill, and many settlements across all three regions suffered as a result. The Yethisian Exarch, Aqad, sought to punish the southern Exarchs for their crimes, and so he began to conscript an army from his domain. In 394 IF, amid troubles in Kanik, Aqad marched from Iferi, with a force of 20,000 soldiers, towards the city of Lucria, hoping to depose the Lucrenian Exarch quickly, while most of his forces were scattered. United by mutual enemies, the Lucrenians and the Selucenians had already agreed to exchange intelligence on the situation in the north, and were quickly alerted to Aqad's offensive. War on the not-so-distant horizon, the threatened Exarchs formed the Twin Union, in defence of the south.
In the face of the Yethisian Invasion, the two Exarchies began to assemble a coordinated defensive force, and battle plan. By the time the Yethisians had reached Lucria, and set the city under siege, the Lucrian Exarch, Raba Di Mari, had already assembled most of his forces in the town of Felori, while the Selucian Exarch, Mani Sel-Anganeux, had begun to gather forces from across the Wannib and Fajla marshlands into Selucia. Together, a combined force of 27,000 men were able to relieve the siege and defeat the Yethisian invaders, though at the cost of many Selucian and Lucrian lives.
The Union's victory at Lucria allowed them to broker a peace with the northern Exarchy, in which trading protections were once again restored. Aqad's death during the siege plunged the desert Exarchy into a succession crisis, that resulted in the ascension of Aqad's Mylosian chief vizier to the position of regent, for Aqad's 7-year old son.
Even after the success of the Vengeance Campaign, the Twin Union continues to exist in spirit, the two southern Exarchies maintaining a shared intelligence network. The Lucrenian-Selucenian alliance seems set to continue for many decades more.