https://en.wikipedia.org/wiki/Bar_Kokhba_revolt
Whatever was left of Israel was wiped out 350 years before the collapse of the Western empire.
The Jewish population made up nearly 15% of the Roman Empire, and that number didn't peak until after the Bar Kochba. Jews continued to live in Canaan, but they continued to spread throughout the Empire. They'd already made up a good-sized chunk of Alexandria, Egypt prior to the Roman conquest. Their commercial activities spread over the borders, playing a role in keeping the Romans and Parthians from going at it more than they did. The Jewish population of Mesopotamia was considerable.