These are those who came from Tel Melah, Tel Harsha, Kerub, Addon, and Immer. They weren't able to prove their ancestry, whether they were true Israelites or not:
The sons of Delaiah, Tobiah, and Nekoda, 642.
Likewise with these priestly families: -The sons of Hobaiah, Hakkoz, and Barzillai, who had married a daughter of Barzillai the Gileadite and took that name.
They looked high and low for their family records but couldn't find them. And so they were barred from priestly work as ritually unclean.
The governor ruled that they could not eat from the holy food until a priest could determine their status by using the Urim and Thummim.