Can someone help me with naming conventions

[Danuis]

I’ve seen that tribes often are used for the lands name –

Vasconia for the Vascones,

[A]Media for the Medes –

Sannica for the Sanni?

does this hold true, and is it just for tribes who end in Latin “-I”? What about “Ae” or “A”?

I've also seen as with the Sinti of the Maeotian sea they've been called the "Siraces" - any tips there?

[El Barto]

If it's Latin, then {district} {genitive form of the local tribe} should be enough.

It's for a game, right?

[Danuis]

If it's Latin, then {district} {genitive form of the local tribe} should be enough.

It's for a game, right?

A map, actually. So it's all genitive - I should look into that.