The Roman Empire fell apart by a complex interaction of forces. These forces included civil war, the dividing into the Eastern and Western Empires, a mixture of religious and political events (including the rise of Christianity), the breakdown of central power, bankruptcy, invasion of Germanic tribes penetrating the Rhine fromtier, internal military revolts, and many other factors. What a mess this must have been. On our Island, all this came to a head around 400 AD - 410 AD when the last of the Roman legions were withdrawn from the island.
At this time, it was common practice for Rome to recruit "barbarian" solders to help fill the ranks of the remaining legions. [Barbarian here meaning people alien to Roman culture usually believed to be inferior.] Often, one barbarian tribe was pitted against another barbarian tribe that had been "allies" just months before. What is not readily understood is that it was aginst Roman law for the Roman citizen to carry arms. Thus for hundreds of years, our family who had become "Romanized" would have lost their fighting skills and their weapons. When the legions left the home front, there were very few remaining tribes who could manage a defense against any who wished to take control of the former "Roman" land. The Picts from the north, and the Irish from the west, had already indicated their interest in our family's land even before the last of the legions had withdrawn from it. In spite of this, our Jones family still clung to its Celtic roots, culture, and language. It was the Celtic language, and its social system that remained after the Romans withdrew. Our Jones family would survive to reproduce another day!