the gemara asks twice on the opinion that says megillas ta'anis was annulled by asking that how could the Rabbis re-instate a 'yuntif' to not fast on 3rd of tishrei or 28th of adar if the megilla was annulled already upon bais hamikdash being destroyed. What was the status though during the bais hamikdash era of these days if the events that they wished to commemorate (not writing G-d's name in documents or decree against Torah/milah/shabbos) didn't happen until after the bais hamikdash time anyway? What's the time frame and what was written about those dates prior?
avi friedman, bronx, ny, usa
The events of the third of Tishrei happened during the time of the Beis ha'Mikdash. During the time of the Beis ha'Mikdash, this day was a holiday even before the incident regarding the documents, as when the second Beis ha'Mikdash was built the third of Tishrei started to be a holiday as implied by the Navi (see Rosh Hashanah 18b regarding Tzom ha'Shevi'i). (See the Gevuras Ari as to why they made a holiday due to the Greek incident, which occurred during the time of the second Beis ha'Mikdash, if it was already a holiday during the time of the first Beis ha'Mikdash.)
The events of the 28th of Adar were after the Churban of the second Beis ha'Mikdash, as proven by the Gemara. Clearly there was no celebration of that day beforehand when there was a Beis ha'Mikdash. (The Gemara's question that the earlier one was nullified is not referring to earlier events that happened on the 28th of Adar, but the fact that the other days mentioned in Megilas Ta'anis no longer had to be observed as holidays.)
All the best,
Yaakov Montrose