Isolated nomads progressively spread southwards and reached South Arabia, where the South Arabian language was spoken. They established linguistic contacts back and forth between Syria and South Arabia and their languages. That is why Garbini considers that Arabic does not belong exclusively to either the Northwest Semitic languages (Aramaic, Phoenician, Hebrew, etc.)
Over time, isolated groups migrated southward and reached South Arabia, where they spoke a distinct language. They maintained communication with neighboring regions, including Syria, and their respective languages. Consequently, Garbini concludes that Arabic is not exclusively part of the Northwest Semitic family (Aramaic, Phoenician, Hebrew, etc.).