I'm playing as Saka right now to see the new units. I think I have satisfied the requirements, but I'm not certain which settlements can recruit the Saka hoplites and whatnot.
edit- it appears that the first city which can recruit them is baktra. A given city cannot have a "nomad" or "mixed" hidden resources. You have to NOT choose "migration" and instead built the allied government. This give you access to Hellenistic units.
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