The Thalmor had always been a powerful faction within Summerset Isle, but had also always been a minority voice. During the crisis, the Crystal Tower was forced to give the Thalmor greater power and authority. Their efforts almost certainly saved Summerset Isle from being overrun. They capitalized on their success to seize total control in 4E 22. They renamed the nation Alinor, which hearkens back to an earlier age before the ascendency of man. Most people outside of the Aldmeri Dominion still call it Summerset Isle, either out of peevishness or ignorance.
In 4E 29, the government of Valenwood was overthrown by Thalmor collaborators and a union with Alinor proclaimed. It appears that Thalmor agents had formed close ties to certain Bosmeri factions even before the Oblivion Crisis. The Empire and its Bosmer allies, caught completely off guard, were quickly defeated by the much-better prepared Altmer forces that invaded Valenwood on the heels of the coup. Thus was the Aldmeri Dominion reborn.
Shortly afterward the Aldmeri Dominion severed all contact with the Empire. For seventy years they were silent. Most scholars believe there was some sort of internal strife in Alinor, but very little is known of the factional struggles that went on inside the Dominion while the Thalmor consolidated its power in Summerset and Valenwood.