The language of Sogdian documents represents the western dialects of the tongue, while the eastern branch gave birth to another Iranian language, Yagnobi, spoken nowadays. Sogdian phonetics showed 5 long and 5 short Indo-European vowels, also 2 pairs of diphthongs (ai, au), had the Indo-European schwa, 19 consonant sounds (while l was used only in loanwords, but absent in Sogdian words). The ancient combinations *ft, *ht became voiced bd, gd, which was common among some East Iranian speech.
The grammar, though simplified by new analytic forms, preserved many archaic features, existing in ancient inflected Proto-Indo-European language. Especially those inflections were strictly kept in verbs. A specific trait of Sogdian was losing or preserving the ending depending on the length of stem vowels.
Three varieties of Sogdian script go back to Aramaic alphabets.