What exchanges do coins first appear on?

And by that I mean, where are they before they hit coinbase and kraken? I've noticed "new" coins on coinbase can be over a year old, and right before they hit coinbase they are a lot cheaper. I'm guessing they are sold elsewhere, and ones that show promise eventually end up on the likes of kraken and coinbase. I've tried googling and all I can find are coinbase equivalents. I also don't want to go to a malicious site and get ripped off because I have no idea if it is legit or not.