Omega: My nation is a Naval history, so that could be the basis for our current tensions as we are pushing colonialism in the Southern ocean as well as regions to the East.

As for historic turbulence, Caidia could have had interests and relations with the other cities/kingdoms before Velos consumed them. Starting a long feud that has been fueled by religious differences, and naval competition as well as general hate. I'm sure there have been times of cooperation in the past, but not in this age.