The Gemara on today’s daf asks why we would have thought that these people are free of the laws of arakhin, and answers that we may have followed the teaching of ben Bukhri with regard to the half-shekel and applied it to arakhin, as well.
As the Torah teaches (see 30:11-16) every Jewish adult male was commanded to bring a maḥatzit ha-shekel – a half-shekel – as a donation to the Temple service. It is clear from stories in Tanakh that this obligation was not just for use in the mishkan – the Tabernacle – in the desert, but was an on-going requirement for as long as the Temple stood. The money was used for communal sacrifices throughout the year.
Was this obligation incumbent on the kohanim who worked in the Temple as well as the general community? This question was the center of debate in Yavne after the destruction of the Temple.
Our Gemara relates that ben Bukhri permits kohanim to bring maḥatzit ha-shekel, although they are not required to do so. Rabban Yoḥanan ben Zakkai argued that although this was the position taken by the kohanim, in fact they were obligated in maḥatzit ha-shekel just like every other Jew.
Yavne is an ancient city that is mentioned in the navi, identified with the Judean city called Yavne’el. For a long time it was a Philistine city, near the Mediterranean coast, almost due west of Jerusalem. When King Uziyahu lists the cities whose walls he destroyed in battle, Yavne is mentioned among them (see Divrei HaYamim II 26:6-8).
In the course of putting down the Great Revolt, the Roman general Vespasian captured the city. At that time it apparently attracted many Sages who did not support the rebellion, and when Rabban Yoḥanan ben Zakkai joined them after the fall of Jerusalem it became the spiritual center of the Jewish people, where the Sanhedrin sat for an extended period of time – apparently until the Bar Kokheva rebellion. The main yeshiva, called Kerem B’Yavne, was established there, together with the seat of the Patriarch. Among the projects done in Yavne was the recording of testimony regarding normative procedure in the Temple in different areas of practice, similar to what we find in today’s Gemara regarding ben Bukhri’s statement.