I'm currently on my 4th attempt on playing as barbarians in civ1. I play on random maps so I won't know where all the other civs are, the only thing which I edit is adding a small island with 4 barb cities that are all building legions.
I tried playing on warlord, prince, king. I see no difference between "power" of my barbarian warriors, they are pathetic regardless of the choice. In my current gameplay (king) I lost 107 legions and 5 cavs to take 3 cities (none of which is a capital city), each one of those cities with only one defender defending it. Capital cities seem to be impossible to capture (I'm aware that they get extra bonus against barbs, I'm also aware that civ's last city gets immortality bonus against barbarians). I already tried cheating in barracks into my barbarian cities, I'm not sure if that made any noticeable difference.
I'm wondering how do all of you guys managed to conquer the world as barbs? I'm giving up on average around 100AD because it's impossible to conquer even a single civilization in that time. My records so far are 3 captured cities. I'm wondering what could be done to improve the barb experience a bit.. Someone mentioned above cheating in chariots instead of legions, or even catapults. Emperor diff level if it even changes anything? Sadly legions and cavalry seem to be nearly useless. Regardless, it's quite fascinating to see the barbarian situation in this game from the other side. During normal gameplay I used to panic a little when they landed near my cities. Now I can see that it will take them 30+ units to take a single city, although they tend to pillage everything so there's that too.
Edit:
I experimented a bit with chariots and catapults. Lost 60 catapults, 68 chariots, 30 more legions, all to one capital city, without killing a single unit inside of it. After that I cheated in dozens of artillery and that did the trick. This makes playing as barbarians (at least in dos 1 version) not enjoyable at all, sadly.