This Ivory Icon is located at the Bode Museum in Berlin. Ivory carving was very popular in the Eastern Roman Empire.
The forty martyrs were 40 Roman soldiers of the 4rth century A.D. They were stationed and martyred in Sevasteia, located in the historical lands of the region of Armenia (Present Turkey). They were part of the Legio XII Fulminata.
In 316 A.D. emperor Licinius persecuted Christians in the Eastern half of the Roman empire. According to the sources, the forty Romans were left on a pond to freeze to death because they had confessed their Christian faith.
"...On the frozen pool, which was their field of battle, these martyrs reminded one another that Jesus had fasted for forty days, and that they themselves were forty in number! Let us, in our turn, compare their sufferings with the lenten exercises which the Church imposes on us; and humble ourselves on seeing our cowardice; or, if we begin with fevour, let us remember that the grand thing is to be faithful to the end, and bring to the Easter solemnity the crown of our perseverance. Our forty martyrs patiently endured the cruellest tortures; the fear of God, and their deep-rooted conviction that He had an infinite claim to their fidelity, gave them the victory....The lives of the saints will be of great help to us...for they will teach us how we are to look upon sin, how to avoid it, and how strictly we are bound to do penance for it after having committed it."
1983 Marian House edition of the English translation of Dom Prosper Guéranger's 'The Liturgical Year' by the Benedictines of Stanbrook.)
The veneration of the 40 martyrs is still popular in the east . There is a number of churches dedicated to them.
Their names were: Hesychius, Meliton, Heraclius, Smaragdus, Domnus, Eunoicus, Valens, Vivianus, Claudius, Priscus, Theodulus, Euthychius, John, Xantheas, Helianus, Sisinius, Cyrion, Angius, Aetius, Flavius, Acacius, Ecditius, Lysimachus, Alexander, Elias, Candidus, Theophilus, Dometian, Gaius, Gorgonius, Eutyches, Athanasius, Cyril, Sacerdon, Nicholas, Valaerius, Philoctimon, Severian, Chudion, and Aglaius.