Mormon 6

 As the Nephites approached their final battle, Mormon writes - 

"...behold I, Mormon, began to be old; and knowing it to be the last struggle of my people, and having been commanded of the Lord that I should not suffer the records which had been handed down by our fathers, which were sacred, to fall into the hands of the Lamanites, (for the Lamanites would destroy them) therefore I made this record out of the plates of Nephi, and hid up in the hill Cumorah all the records which had been entrusted to me by the hand of the Lord, save it were these few plates which I gave unto my son Moroni."  (Mormon 6:6)

Obviously, Mormon deposited all the records of the Nephites in the hill Cumorah.