One of the most important watersheds in the history of Roman glassworking occurred during the two decades following A.D. 312. It was then Emperor Constantine embraced Christianity and, following a political rift with the Senate in Rome, moved the administrative heart of the Empire to the site of ancient Byzantium, at the southeastern corner of the Black Sea. He named his new city Constantinople.
That move, as a historical event, was in itself sufficient to strongly influence the course of glassworking, simply by revitalizing the economies of the neighboring eastern provinces. But Constantine did far more than that. He specifically granted tax exemptions to many groups of craftsmen, including glassworkers, so that "...they might become more skilled in their art and see to the training of their sons." (Codex Theodosius 13.4.2)