en_tn/act/11/02.md

had come up to Jerusalem

Jerusalem was higher than almost any other place in Israel, so it was normal for Israelites to speak of coming up to Jerusalem and going down from it.

they who belonged to the circumcision group

This is a reference to some of the Jews who believed that every believer must be circumcised. AT: "some Jewish believers in Jerusalem who wanted all followers of Christ to be circumcized" (See: rc://en/ta/man/translate/figs-metonymy)