It can be either. The different factions of the same race can have slightly different rules so you generally stick to their colour scheme. However you can just make one up and say it's a sub-faction, the downside is there's no fluff for your army unless you make it up yourself
It can be either. The different factions of the same race can have slightly different rules so you generally stick to their colour scheme. However you can just make one up and say it's a sub-faction, the downside is there's no fluff for your army unless you make it up yourself