Mai Chanukka? What is the question?

I'm a big fan of determining how to parse ambiguous pesukim and gemaras. And the one for Chanukka is a good one. Furthermore, the correct parse in this case is important to determining the date of a specific piece, which is in turn important for further analysis.

"מאי חנוכה, דתנו רבנן, בכ"ה בכסליו יומי דחנוכה תמניא אינון, דלא למספד בהון ודלא להתענות בהון (מגילת תענית, משנה כ"ג). שנכנסו יוונים להיכל, טימאו כל השמנים שבהיכל וכשגברה מלכות בית חשמונאי ונצחום,בדקו ולא מצאו אלא פך אחד של שמן, שהיה מונח בחותמו של כהן גדול, ולא היה בו אלא להדליק יום אחד.נעשה בו נס, והדליקו ממנו שמונה ימים. לשנה אחרת קבעום ועשאום ימים טובים בהלל והודאה". (גמרא שבת כא

The standard parse of the question I've heard is as the OU gives on this webpage, appropriately titled "What is Chanuka?":

"What is Chanukah? The Rabbis have expounded: Beginning with the 25th of Kislev, eight days of Chanukah are observed, during which no eulogies are delivered, nor is fasting permitted. For when the Greeks entered the Sanctuary, they defiled all the holy oils used for the Menorah in the temple, and when the Hasmonean house prevailed and vanquished them, they searched and found only one remaining jar of oil with the Kohen Gadol's seal.
Although it contained only enough oil to burn for one day, a miracle occurred, and the oil burned for eight days. A year later they (the Rabbis) designated these days as Yamim Tovim (holidays) on which praise and thanksgiving were to be said." (Tractate Shabbat 21)

However, there are two things which potentially argue against this parse. First, there is a shift from Hebrew to Aramaic. בכ"ה בכסליו יומי דחנוכה תמניא אינון, דלא למספד בהון ודלא להתענות בהון is Aramaic and the rest of the gemara is quite obviously Hebrew. Second, this portion in Aramaic is a direct quote from Megillat Taanit, which is a scroll containing days upon which one should not fast or make eulogies because of great things that happened on those days.

However, the Hebrew also appears to be a direct quote from the Hebrew Scholium to Megillat Taanit, and appears just as it does here. The entire thing may then be a quote from Megillat Taanit.

On the other hand, while the Aramaic portion of Megillat Taanit is surely Tannaitic, according to the Talmud from Hananiah ben Hezekiah ben Gurion, student of Shammai from early 1st century CE, the dating of the Hebrew Scholium is unclear, with many dating it to post-Talmudic times. (When I first searched for this, I found someone dating it to around the same time as the Aramaic, and my earlier post worked on that premise.) Furthermore, we have the ד on דתנו רבנן.

I would thus parse it instead, "What is this 'Chanukka" about which the Sages learnt in {in Megillat Taanit} that 'Starting on the 25th of Kislev are the 8 days of Chanukka, during which one should not deliver a eulogy nor fast?"

The gemara then answers on its own or cites another source שנכנסו יוונים להיכל, טימאו כל השמנים שבהיכל וכשגברה מלכות בית חשמונאי ונצחום,בדקו ולא מצאו אלא פך אחד של שמן, שהיה מונח בחותמו של כהן גדול, ולא היה בו אלא להדליק יום אחד.נעשה בו נס, והדליקו ממנו שמונה ימים. לשנה אחרת קבעום ועשאום ימים טובים בהלל והודאה

Thus, we understand the reference to 'Chanukkah' mentioned in Megillat Taanit, which is important, for Megillat Taanit was nullified except for Purim and Chanukkah.

Indeed, that is how I parsed it in my translation for the Rif.

The dating of this section of gemara's explanation is then unclear. It could be as late as Ravina II, though it could also be earlier, and regardless, it could be an explanation known through Oral Tradition from much earlier.

But the important conclusion of this is that the fact that it states "Tno Rabbanan" and that the Hebrew explanation appears in Megillat Taanit does not (necessarily) mean that the explanation is an early source.