User blog comment:BioChimes/Ork Clan vs Ork Tribe/@comment-33731050-20150501005923/@comment-24909831-20150501125805

I think people need to stop linking 40k Wikia untill they figure out the meaning of sources and sourcing.

And it says on that same page 12: "there are six clans that have spred from one side of the galaxy to the other". It does not say: "there are only six clans...". I can't find any reference in that to tribes or empiric cultures. It does however say, on the same page: "...tribe is simply all Orks [...] regardless of what kult or clan they may belong to...", which clearly implies that tribe is separate thing from clan.

I don't think there is any reason to ponder on this. Tribe is not the same thing as clan, but tribe may be built up only of orks of a single clan. Clan is not the same thing as tribe, even if the tribe would've been made up of orks of a single clan. It is still a tribe, which follows this "philosophy" of a clan.