The province - Judaea was no longer a kingdom, but a mere “province” of Persia. “The children of the province” are the Israelites who returned to Palestine, as distinct from those who remained in Babylonia and Persia.
Every one unto his city - That is, to the city whereto his forefathers had belonged. Of course, in the few cases where this was not known Ezra 2:59-62, the plan could not be carried out.
Two other copies of the following list have come down to us - one in Nehemiah 7:7-69, and the other in 1 Esdras 5:8-43. All seem to have been taken from the same original document, and to have suffered more or less from corruption. Where two out of the three agree, the reading should prevail over that of the third.