The Syrian Influence on Iconography

There are many different styles from different regions, but this is in regards to the Syrian influence. I was told by someone else who is very knowledgeable in this area that some of the earliest Syrian Icons didn't include a beard. But this is what the Blackwell Dictionary of Eastern Christianity had to say:

The eastern provinces of the Roman empire were heirs of the civilizations of Egypt, Syria and Mesopotamia. The link between early Christian portrait icons and Egyptian funerary portraits is evident. But it is the Syrian physical type which eventually became established in Christian iconography for the portrait of Christ, a bearded figure with full dark hair falling over his forehead, large almond eyes, straight nose and small lips. The reign of the Roman Emperor Justinian (527-65) marks a turning point in art. His support of the arts was part of his mission to civilize, Christianize and unify God's terrestrial Kingdom, of which he was the viceroy. In his capital emerged a synthesis of classical, late antique and hieratic eastern stylistic elements. Justinian's Divine Wisdom (523-7) expresses the world view of imperial Christianity. In the sixth century all the essential elements of a truly Christian stylistic system had already been forged and synthesized. Iconography entered a new phase when canon 82 of the Quinisext Council (692) prohibited symbolic images of Christ, prescribing portrayal of Christ in his human form so that "we comprehend thereby the humility of God the Word, and are guided to the recollection of his way of life in the flesh". Although Byzantine ICONOCLASM in the eighth and ninth centuries challenged the validity of the portrayal of Christ and of the cult of icons, the 'Triumph of Orthodoxy' in 843 promoted a creative synthesis of theology and religious art that was of great significance for the subsequent history of European art.

The Blackwell Dictionary of Eastern Christianity, page 244,
edited by Ken Parry, David J. Melling, Dimitri Brady,
Sidney H. Griffith, and John F. Healey.
Blackwell, 1999, 2001.