I want to know the answer to the following question:
What may have also been in use at the time?
All the background I'm provided with is that "Good candidates are the hypothethical ancestor languages of Alanian/Scytho-Sarmatian subgroup of Scythian in the far northwest; and the hypothetical "Old Parthian" (the Old Iranian ancestor of Parthian) in the near northwest, where original". Is that enough to answer the question?
Answer: no