There was a constant small jewish population in the land of israel ever since the 70a.d exile. Also families moved back in the middle ages.
The jews were always a separatist community, due to them being used as scapegoats by the local rulers (started from the usury days, when the local aristocrats made jews their money loan frontmen) and persecuted by local mobs. The separatist nature went on up until the 18th century when the western jews began to assimilate.