During the hundreds of years when the Nephites and Lamanites had lived apart, their languages had changed to such an extent that it was difficult for them to communicate with each other. During the period of history between 145 and 123 B.C., however, the king of the Lamanites "appointed teachers of the brethren of Amulon" (the wicked priests of King Noah who were Nephites by birth) to teach the Nephite language "among all the people of the Lamanites." (Mosiah 24:4.) Thus the two groups evidently start speaking the same language again. This fact takes on added significance later in the Book of Mormon when we read about the missionary efforts between these two groups.