How were ת & ט pronounced historically?
In Sephardi or Israeli Hebrew today, ט and ת are pronounced the same, at least to my non-native ear, something like /t/. In Ashkenazi Hebrew, on the other hand, sometimes ת is pronounced like ס (samech), /s/. Was there a pre-modern time when they were pronounced differently? If so, how?
I'm wondering whether there was a different original pronunciation of ת, one that was different from ט and from ס, that none of these groups preserved, or if it was always a variation (multiple pronunciations were used historically), or if it is a more recent regional variation.
This question is one aspect of a broader "how did Sephardi and Ashkenazi variations develop?" question, but I thought that would be too broad. If I'm wrong about that, I'm happy to accept a broader answer and adjust the question to suit.
I'm aware that some people also pronounce ת like the soft "th" in English, /θ/. I have the impression that's newer but might be wrong.