D. Limits of Time Within Which the Total Extinction of Tekhelet shel tzitzit – the Tekhelet of the tzitzit – Must Be Placed
Tekhelet was imported into Babylonia by Mar of Mashki “in the years of Rab Ahai.” It was probable that this R. Ahai is identical with the Amora of that name who was described by the Palestinian teachers of the law as “the light of the eyes of the exile.” (מאיר עיני הגולה). As he died about 506 this would be the latest record of an importation of Tekhelet for tzitzit into Babylonia.
The phrase “in the years of Rab. Ahai” indicates a considerable lapse of time; the passage is probably a late Saborean addition. It may safely be asserted that at the time of the completion of the Talmud (c. 570) Tekhelet still continued in practice for tzitzit, for there is nowhere in the Talmud the slightest allusion to the discontinuance of the rite.
On the other hand in the Sheiltot d’Rab Ahai, a ritual work composed in Palestine about 760 all mention of Tekhelet is omitted. The disappearance of Tekhelet from the Jewish ritual thus falls between the final redaction of the Talmud by the Saboraim (c. 570) and the composition of the Sheiltot (760). From the entire absence of a reference to Tekhelet in the Sheiltot, I should conclude that Tekhelet shel tzitzit תכלת של ציצית must have been long extinct by the beginning of the eighth century.
The Arab conquests of Palestine about 639 entailed the total destruction of the purple dyehouses administered by the imperial officials.1 Was this the real cause of the extinction of Tekhelet?
Benjamin of Tudela (travelled 1160-1173) makes mention of purple dyeing on the Tyrian Coast.2 It would thus appear that the industry revived some time after the Arab occupation. The interval must have been a fairly long one seeing that the Jews who in Benjamin’s time played an important part in the industrial life of Tyre3 had made no attempt to resuscitate Tekhelet-dyeing; the chain of tradition must have been too long broken.
It is probable that the fixing of the halakhah (religious practice) in accordance with the opinion which held Tekhelet not to be a Sine Qua Non of the tzitzit was responsible to a great extent for the gradual extinction of ritual Tekhelet.
In the Midrash Tanhuma and Midrash Rabbah section שלח it is stated: “at the present time we have no Tekhelet but only lavan (white thread) in the tzitzit, for Tekhelet has been hidden (treasured up).”
ועכשיו אין לנו תכלת אלא לבן תכלת נגנז
The redaction of these Aggadic collections falls about 750. There is probably an allusion here to the Sifre, Deut. 33.