From Alathra Wiki

Before there was a Nation in Nevadia there was the USA and a small town named New Vegas, UsaZach decided to settle in this land because of its proximity to the large Mesa he also was protected by the USA which gave extra reason to settle in this land New Vegas slowly evolved into a mining settlement rich in gold,diamonds and iron with this new found wealth they founded a nation named Nevadia

Nevadian capital New Vegas

After the outbreak of the Acquavendia-USA war Nevadia lost it's closest ally and it's brother city of New Reno.After said war Nevadia entered a long period of stagnation Nevadia stopped growing,stopped building,had no new cities until Bunkur 13 joined ,but still the stagnation continued. Then Acquavendia declared war on all towns and nations on the continent of Prospit this created a shock in New Vegas they went so far as to prepare an escape.On that day the people of Nevadia bielived the sun would set once and for all on their nation,But then prince UsaZach got an invitation from Thaeorn to join the resistance, an opposition group to fight Grandpa_Boob and his desire of uniting Prospit under his rule.