The fun thing about Akaviri lore is that not much is actually known, so how the http://www.uesp.net/wiki/Lore:Ka_Po%27_Tun came around is truly a mystery and still being investigated within the lore. I love how the world and it's lore is progressing in real time with us as we play it all out. :hehe:
Also, in Oblivion there is a rumor that the Neravarine went over there on an expedition and was never heard of ever since.
Because the Nerevarine isn't affected by age, maybe he/she came back in the last couple hundred years and wrote a book about his/her adventures in Akavir.
Finding a book in Skyrim written by your Morrowind character would be awesome.