What does Nehemiah 13:6 mean?

But while all this was happening, I wasn’t in Jerusalem, because in the thirty-second year of King Artaxerxes of Babylon, I had gone back to the king. Later, I asked for permission to return. Nehemiah 13:6 - Modern Text Bible

(Nehemiah explains he was away from Jerusalem for a while, having returned to serve the Persian king. He only found out about these problems when he came back.)