I'm making a baltic prussian course on tinycards
Ummm. Sorry. Just spreading language love.
That's awesome (I'll try not to make assumptions based on your profile picture)!
I know little about Baltic Prussian and Prussia in general, except for the fact that Prussia doesn't exist anymore. If it wasn't for Hetalia, I wouldn't even know about its temporary existence (that goes for many other nations as well).
The nation of Prussia was a German-speaking nation and was a catalyst in the creation of the unified nation we today call Germany.
Baltic Prussian is a language that finally died off in the early 1700s and is related to the modern Lithuanian and Latvian languages. Old Prussian was spoken in what is today northeastern Poland.