Hi
Am currently playing a BKB campaign (my first, actually), and yes, BKB observes the 'practice' (as do most MTW mods in my experience, along with vanilla) that certain units only become available as you move from one era to the next.
Actually, units only becoming available at certain times, or even disappearing from the roster, adds to the game's character for me. No criticism. Obviously it's a matter of taste.
Best regards
Victor
Sapere aude
Horace
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