This is an ivory frieze that was found in one of the Terrace Houses at Ephesus. It dates to the second century AD. It could have belonged to a lintel or some furniture. The frieze shows the Emperor Trajan and the Roman army in a victorious campaign against the Dacians (like the Column of Trajan in Rome) or the Parthians.
Note the three panels that are separated by two "Caryatids"—like the Erechtheion on the Acropolis in Athens.
See here for a detail of the well-preserved left panel.
The total length of the frieze is about 3 ft.