Please feel free to correct the list and then i will update it.
AFR = African
ARA = Arab
ARM = Armenia
BAL = Balkanic (Illyrian and more interior tribes)
BRT = Briton
CAR = Carthaginian
CEL = Celtic
COL = Colchis
CRE = Cretan
CMN = Common
DAC = Dacian
GER / GRM = Germanic
GLL = Gallician
GLT = Galatian
HEL = Hellenistic
IBE = Iberian (of the Caucasus, not Hispanian)
IBR = Iberic
ITA / ITL = Italic
JUD = Judean
LAG = Lagides (Ptolemaic Egypt)
MAC = Macedonian
MAU = Mauretanian
NOM = Nomadic
NUM = Numidian
PAR = Parthian
PIR = Pirate
PON = Pontic
PSA = Persian
RHO = Rhodian
ROM = Roman
SAR = Sarmatian
SCY = Scythian
SMN = Samnite
SYR = Syrian
THR = Thracian