Right. I think that there's a grouping of tribes linguistically
under a heading of "Atakapan" that includes the Opelousas tribe
in Louisiana and some in Texas. The tribe I referred to are the
only that I know of using the name in recent historical times, but
I'm not familiar with the early Texas tribes. The Southern region
generally tended to see several bands fractured and dispersed within
and between states--for instance the Koasati in Louisiana are of the
same historic tribe as the Coushatta in Texas, who share a reservation
with the Alabama tribe that relocated there from, well, present-day
Alabama. There might be more information on the Atakapan cultures
in Texas historical dialogues than Southeastern ones; the Louisiana-
Texas border arbitrarily became a border of research for Swanton and
others as well, I'd imagine.
Arlen