Where do Chariots come from? I've researched their tech, and hoped the Stables would tell me I had to upgrade that building to a higher level, as the Garrison does for Centurions, and the Hunter's Hovel for Archers, but it's not sayin' nuthin'!
And I don't see an alternative. Certainly it can't be the Nomads' Yard!
Later: Turns out to be the Colosseum, at least at L.3, which before my Research didn't HAVE a training slot! And which doesn't, in fact, have one at L.1. This is NOT good guidance.
Even later: When you point at the Upgrade button when contemplating L.2, it does say that allows you to train Chariot. But the L.1 description doesn't tell you about the next level. And there's positive rather than negative culture, as for the other fighter-training buildings.