Why were the Goths featured in Age Of Kings?

I've been wondering a lot about this. I love playing the Goths, it's great fun, yet they are so out of context. Okay, they found the first lasting empire on the ruins of the Roman Empire. But the whole thing hardly lasted a century. By the VIII. century they were almost extinct.

However the game [Age Of Kings] takes place from around the X. century (but rather a bit latter) to almost the end of the middle ages.

It is kind of stupid when the Polish appear in the Barbarossa campaign as Goths. I know there are many historical errors in the game, but this one seems to be the biggest: They included a civilisation that existed centuries before the others and wasn't even used in any campaign as themselves (in AoK).

Thoughts?