This was Jerusalem. Romans and their ancestors were left after the formation of the Church during Constantine reign. No doubt, the monasteries had been occupied off and on since then. Jericho was more of a crossroads, so more civilizations have remnants there.
Romans and their descendants, I think you mean. The point is, its not an unknown practice in the region, or indeed throughout the world. It would be nice if grave markers were present at this Sussex dig, but that rarely happens. With ancient burials, either the markers are found (and sometimes had been reused at least once as building materials etc) without any sign of the remains, or remains are found without any markers (as happened with a very high status burial at Sutton Hoo, from Anglo-Saxon times, hardly a prehistoric era).