According to my handy copy of “Georgia Place Names” by Krakow we have:
APALACHEE,This is the oldest recorded Indian
name in Georgia, according to Goff. It is a name
that was given to a former community in Oconee
County, and was named for the APALACHEE
RIVER on which it was located. This was formerly
called the South Branch of the Oconee River, and
before that named CHULAPOCCA (q.v.). There
is at present a community called APALACHEE
in upper Morgan County. It was settled before 1820
and incorporated August 22, 1907 to July 1, 1995.
The railroad station here was first named FLORENCE,
for Florence Few, a daughter of Joe C. Few.
The name was already in use, so about 1896 the
name Apalachee was adopted. The name is derived
fromthe Apalachee (or Apalachi) Indian tribe of
the Creek Confederation. The meaning may be from
the Hitchiti Indian word apalahchi, “those on the
other side” (as opposed to allies), “those who lived
beyond the mountains,” or possibly from the
Choctaw, apelachi, “helpers” or “allies.” Derivation
can also be traced from the former Indian town
of Apalachee (or Apalachen), which was in the
vicinity of today’s Tallahassee, Florida. This place
wasmentioned by Alvar Nunez de Vaca.(c.1490-
1557) in the account of the Narvaez expedition
of 1528. The Spaniards under Hernando De Soto
(1500?-1557) first applied the name to the
APPALACHIAN MOUNTAINS in 1539. This range
includes all of the eastern United States mountains
from Alabama and Georgia to northern Maine.
Through this range runs the APPALACHIAN
TRAIL, one of the longest trails in the world, which
extends 2,065 miles from Springer Mountain in
Georgia to Mount Katahdin in Maine.
Sorry about the formatting.
Good reference; thanks.