Release was 50. If you want to go all the way back to JP release. NA got Rise of the Zilart with the game release which was indeed level cap 70. Which was raised to 75 before any NA had even come close to the 70 cap.
Edit: Also Sky was the first expansion. 2nd expansion was Chains of Promatia, which was Sea. I'm pretty sure something around 75% of players hadn't even got to Sky by the time COP had been released...