The most important part of Nehemiah, not often mentioned, is that it puts a time and date on the commandment to rebuild Jerusalem.
Nehemiah 2:1 And it came to pass in the month Nisan, in the twentieth year of Artaxerxes the king, that wine was before him: and I took up the wine, and gave it unto the king. Now I had not been beforetime sad in his presence. [kjv]
2:5 And I said unto the king, If it please the king, and if thy servant have found favour in thy sight, that thou wouldest send me unto Judah, unto the city of my fathers' sepulchres, that I may build it. [kjv]
2:6 And the king said unto me, (the queen also sitting by him,) For how long shall thy journey be? and when wilt thou return? So it pleased the king to send me; and I set him a time. [kjv]
The Hebrew and Babylonian month of Nison is traditionally in the spring. This precise date (e.g., in the
NIV (New International Version)), has been dated to August of 445 BC or 444 BC., about 100 years after the 70 weeks prophecy of Daniel.
Note: Ezra/Nehemiah were originally
one book, not two.