People, the dragons are not from Akavir. http://www.imperial-library.info/content/nu-mantia-intercept.
"Then will mighty Akatosh reply, wherein the petitioner must be demand full freedom! To speak in the fires of time is to render the speaker a subject of the matron Jills, those servants of the Dragon that mend minutes without volunteer. Only through freedom can true words remain untouched."
http://www.uesp.net/wiki/Lore:Mysterious_Akavir
like with real history, you need to look at different sources and read between the lines if you want to be a historian instead of a theologist.
"Ka Po' Tun is the "Tiger-Dragon's Empire". The cat-folk here are ruled by the divine Tosh Raka, the Tiger-Dragon. They are now a very great empire, stronger than Tsaesci (though not at sea). After the Serpent-Folk ate all the Men, they tried to eat all the Dragons. They managed to enslave the Red Dragons, but the black ones had fled to (then) Po Tun. A great war was raged, which left both the cats and the snakes weak, and the Dragons all dead. Since that time the cat-folk have tried to become the Dragons. Tosh Raka is the first to succeed. He is the largest Dragon in the world, orange and black, and he has very many new ideas."
http://www.uesp.net/wiki/Lore:Varieties_of_Faith...
"Alduin (World Eater): Alduin is the Nordic variation of Akatosh, and only superficially resembles his counterpart in the Nine Divines. For example, Alduin's sobriquet, 'the world eater', comes from myths that depict him as the horrible, rauaging firestorm that destroyed the last world to begin this one. Nords therefore see the god of time as both creator and harbinger of the apocalypse. He is not the chief of the Nordic pantheon (in fact, that pantheon has no chief; see Shor, below) but its wellspring, albeit a grim and frightening one."