“Then my God put it into my mind to assemble the nobles and the officials and the people to be enrolled by genealogy. I found the book of the genealogy of those who were the first to come back.”
Nehemiah has God tell him to enroll everyone in a book of genealogy. He found the book of genealogy about those who had returned after the exile. The important people were captured by King Nebuchadnezzar around 582 BCE. This return is around 537 BCE so that some of these people may have still been living. Although the prophet Jeremiah had predicted 70 years, that might include the years of the first attack. If not the original captured people, certainly these were their sons or grandsons.